Based on the provided template and the requirement to adapt it for the unit 'coulomb (C)' under 'Electric Charge', here is the PHP code:



<main class="container">
    <div class="content-card">
        <h1>Coulomb Conversion Tool - Convert Coulombs to Any Unit</h1>

        <!-- Converter Section -->
        <section class="converter">
            <h2>Convert Coulombs to Other Units</h2>
            <div class="converter-container">
                <div class="converter-layout">
                    <div class="converter-input-group">
                        <label for="chargeValue" class="converter-label">Enter value</label>
                        <input type="number" id="chargeValue" placeholder="Enter value" step="any" class="large-input">
                        <select id="fromUnit">
                            <option value="C">Coulomb (C)</option>                        </select>
                    </div>
                    <div class="converter-controls">
                        <button id="swapUnits" class="swap-button" title="Swap units">
                            <i class="fas fa-exchange-alt"></i>
                        </button>
                    </div>
                    <div class="converter-output-group">
                        <label for="resultValue" class="converter-label">Result</label>
                        <div id="resultValue" class="result-display">Result</div>
                        <select id="toUnit">
                            <option value="Ah">Ampere-hour (Ah)</option><option value="mAh">Milliampere-hour (mAh)</option><option value="F">Faraday (F)</option><option value="e">Elementary charge (e)</option><option value="statcoulomb">Statcoulomb</option>                        </select>
                    </div>
                </div>
                <div class="quick-conversions">
                    <h3>Quick Conversions</h3>
                    <div class="quick-buttons">
                        <button class="quick-convert" data-value="1">1 C</button>
                        <button class="quick-convert" data-value="10">10 C</button>
                        <button class="quick-convert" data-value="100">100 C</button>
                        <button class="quick-convert" data-value="1000">1000 C</button>
                        <button class="quick-convert" data-value="10000">10000 C</button>
                    </div>
                </div>
                <div class="decimal-controls">
                    <label for="decimalPrecision">Decimal Places:</label>
                    <button id="decreaseDecimals" type="button">-</button>
                    <span id="decimalPrecision">Auto</span>
                    <button id="increaseDecimals" type="button">+</button>
                    <button id="resetConverter" type="button">Reset</button>
                </div>
            </div>
        </section>
        
        <section class="converter">
            <h2>Convert Other Units to Coulombs</h2>
            <div class="converter-container">
                <div class="converter-layout">
                    <div class="converter-input-group">
                        <label for="chargeValue2" class="converter-label">Enter value</label>
                        <input type="number" id="chargeValue2" placeholder="Enter value" step="any" class="large-input">
                        <select id="fromUnit2">
                            <option value="Ah">Ampere-hour (Ah)</option><option value="mAh">Milliampere-hour (mAh)</option><option value="F">Faraday (F)</option><option value="e">Elementary charge (e)</option><option value="statcoulomb">Statcoulomb</option>                        </select>
                    </div>
                    <div class="converter-controls">
                        <button id="swapUnits2" class="swap-button" title="Swap units">
                            <i class="fas fa-exchange-alt"></i>
                        </button>
                    </div>
                    <div class="converter-output-group">
                        <label for="resultValue2" class="converter-label">Result</label>
                        <div id="resultValue2" class="result-display">Result</div>
                        <select id="toUnit2">
                            <option value="C">Coulomb (C)</option>                        </select>
                    </div>
                </div>
                <div class="quick-conversions">
                    <h3>Quick Conversions</h3>
                    <div class="quick-buttons">
                        <button class="quick-convert" data-value="1">1 C</button>
                        <button class="quick-convert" data-value="10">10 C</button>
                        <button class="quick-convert" data-value="100">100 C</button>
                        <button class="quick-convert" data-value="1000">1000 C</button>
                        <button class="quick-convert" data-value="10000">10000 C</button>
                    </div>
                <div class="decimal-controls">
                    <label for="decimalPrecision2">Decimal Places:</label>
                    <button id="decreaseDecimals2" type="button">-</button>
                    <span id="decimalPrecision2">Auto</span>
                    <button id="increaseDecimals2" type="button">+</button>
                    <button id="resetConverter2" type="button">Reset</button>
                </div>
            </div>
        </section>

        <section class="top-units">
            <h2>Related Electric Charge Units</h2>
            <div class="units-grid">
                <a href="/electric-charge/ampere-hours/" class="unit-card-link">
                    <div class="unit-card">
                        <h3>Ampere-hour (Ah)</h3>
                        <p>3,600 coulombs - used for battery capacity</p>
                    </div>
                </a>
                <a href="/electric-charge/milliampere-hours/" class="unit-card-link">
                    <div class="unit-card">
                        <h3>Milliampere-hour (mAh)</h3>
                        <p>0.001 ampere-hours - common for small batteries</p>
                    </div>
                </a>
                <a href="/electric-charge/faradays/" class="unit-card-link">
                    <div class="unit-card">
                        <h3>Faraday (F)</h3>
                        <p>Approximately 96,485 coulombs - used in electrochemistry</p>
                    </div>
                </a>
                <a href="/electric-charge/elementary-charges/" class="unit-card-link">
                    <div class="unit-card">
                        <h3>Elementary charge (e)</h3>
                        <p>1.602176634×10⁻¹⁹ C - the charge of a proton or electron</p>
                    </div>
                </a>
            </div>
        </section>

        <section class="conversions-table">
            <h2>Coulomb Conversion Table</h2>
            <p>This comprehensive coulomb conversion table shows how various electric charge units relate to coulombs, the SI base unit for electric charge. Use this reference for quick conversions between coulombs and other common electric charge units.</p>
            <div class="converter-container">
                <table class="conversion-table styled-table">
                   <thead>
                       <tr>
                           <th scope="col">Conversion</th>
                           <th scope="col">To Unit</th>
                           <th scope="col">Multiplier</th>
                       </tr>
                   </thead>
                   <tbody>
                       <tr>
                           <td><a href="/electric-charge/coulombs/c-to-ah">Coulombs to ampere-hours</a></td>
                           <td><a href="/electric-charge/ampere-hours">Ampere-hours</a></td>
                           <td>0.000277778</td>
                       </tr>
                       <tr>
                           <td><a href="/electric-charge/coulombs/c-to-mah">Coulombs to milliampere-hours</a></td>
                           <td><a href="/electric-charge/milliampere-hours">Milliampere-hours</a></td>
                           <td>0.277778</td>
                       </tr>
                       <tr>
                           <td><a href="/electric-charge/coulombs/c-to-f">Coulombs to faradays</a></td>
                           <td><a href="/electric-charge/faradays">Faradays</a></td>
                           <td>1.0364×10⁻⁵</td>
                       </tr>
                       <tr>
                           <td><a href="/electric-charge/coulombs/c-to-e">Coulombs to elementary charges</a></td>
                           <td><a href="/electric-charge/elementary-charges">Elementary charges</a></td>
                           <td>6.2415×10¹⁸</td>
                       </tr>
                       <tr>
                           <td><a href="/electric-charge/coulombs/c-to-statcoulomb">Coulombs to statcoulombs</a></td>
                           <td><a href="/electric-charge/statcoulombs">Statcoulombs</a></td>
                           <td>2.9979×10⁹</td>
                       </tr>
                   </tbody>
               </table>
            </div>
            <p>This coulomb conversion reference table provides accurate conversion factors for various electric charge units. All values are based on internationally recognized standards for maximum precision in scientific and engineering applications.</p>
        </section>

        <section class="explanation">
            <h2>What is a Coulomb?</h2>
            <p>The coulomb (symbol: C) is the SI unit of electric charge. It is defined as the charge transported by a constant current of one ampere in one second. This definition makes the coulomb one of the seven base units in the International System of Units (SI).</p>
            <p>The coulomb is used worldwide as the standard unit for measuring electric charge, forming the foundation for other units in the field of electricity. Our <a href="/electric-charge">coulomb conversion tool</a> helps you easily convert between coulombs and other units. For example, 1 coulomb equals approximately 0.000277778 ampere-hours or 6.2415×10¹⁸ elementary charges.</p>
        </section>

        <section class="definition">
            <h2>What is the SI of Coulomb?</h2>
            <p>The coulomb is one of the seven base units in the International System of Units (SI). It serves as the fundamental unit for measuring electric charge. The coulomb is defined in terms of the ampere, another SI base unit, making it essential for <a href="/electric-charge">electric charge conversions</a>:</p>
            <ul>
                <li>Ampere-hour (Ah) = 3,600 coulombs</li>
                <li>Milliampere-hour (mAh) = 3.6 coulombs</li>
                <li>Faraday (F) ≈ 96,485 coulombs</li>
                <li>Elementary charge (e) ≈ 1.602176634×10⁻¹⁹ coulombs</li>
            </ul>
        </section>

        <section class="uses">
            <h2>What are Coulombs Used For?</h2>
            <p>Coulombs are used in a wide range of applications across physics, engineering, electronics, and electrochemistry. As the base SI unit for electric charge, coulombs provide a standard for all <a href="/electric-charge">electric charge conversions</a>:</p>
            <div class="use-cases-grid">
                <div class="use-case-card">
                    <h3>Electronics & Electrical Engineering</h3>
                    <p>Circuit analysis, capacitor specifications, and electrical calculations. For example, measuring the charge stored in a capacitor or the total charge passing through a circuit component.</p>
                </div>
                <div class="use-case-card">
                    <h3>Electrochemistry</h3>
                    <p>Battery capacity, electrolysis calculations, and Faraday's laws. For example, determining the amount of charge required to electroplate a specific amount of metal.</p>
                </div>
                <div class="use-case-card">
                    <h3>Physics Education</h3>
                    <p>Teaching fundamental concepts of electricity and magnetism. For example, calculating the force between charged particles using Coulomb's law.</p>
                </div>
                <div class="use-case-card">
                    <h3>Research & Development</h3>
                    <p>Scientific experiments and high-tech manufacturing. For example, measuring charge in particle accelerators or in the development of electronic components.</p>
                </div>
            </div>
        </section>

        <section class="history">
            <h2>Etymology and History</h2>
            <p>The unit "coulomb" is named after the French physicist Charles-Augustin de Coulomb (1736-1806), who was famous for developing Coulomb's law, which describes the electrostatic force between charged particles. The coulomb was officially adopted as the SI unit of electric charge in 1881.</p>
            <p>Originally, the coulomb was defined in terms of the ampere and time. Since 2019, the definition has been refined to be based on the elementary charge, making it more precise and consistent with fundamental physical constants. This evolution reflects the advancement of measurement science and the need for more accurate SI units.</p>
        </section>

        <!-- FAQs Section -->
        <section class="faqs">
            <h2>Frequently Asked Questions</h2>
            <div class="faq-item"><h3>Why is the coulomb the base unit of electric charge?</h3><p>The coulomb was chosen as the standard SI unit because it provides a convenient scale for practical electrical measurements and can be precisely defined using fundamental physical constants. Its definition based on the ampere and time makes it universally reproducible and essential for all electric charge conversions. This foundation ensures consistency in scientific research, engineering projects, and commercial applications.</p></div>
            <div class="faq-item"><h3>How accurate is the coulomb definition?</h3><p>The current definition of the coulomb is extremely accurate, derived from the fixed value of the elementary charge. This definition allows the coulomb to be reproduced with an accuracy of better than one part in a billion, making it one of the most precisely defined SI units. Such precision is crucial for advanced scientific research and high-tech manufacturing.</p></div>
            <div class="faq-item"><h3>How do I convert coulombs to other units?</h3><p>Use our coulomb conversion calculators above, or multiply by the appropriate conversion factor. For example, to convert coulombs to ampere-hours, multiply by 0.000277778; to convert coulombs to milliampere-hours, multiply by 277.778. For detailed instructions on converting coulombs to ampere-hours, visit our <a href="/electric-charge/coulombs/c-to-ah">coulomb to Ah converter</a>. Our tool also handles conversions to faradays and elementary charges with high precision.</p></div>
            <div class="faq-item"><h3>What are common uses for coulomb conversion?</h3><p>Coulomb conversion is essential in electrical engineering (circuit analysis), electrochemistry (battery calculations), physics education (student assignments), and research (experimental measurements). Whether calculating capacitor charge or determining the amount of material deposited in an electroplating process, our coulomb converter tool simplifies these everyday tasks.</p></div>
            <div class="faq-item"><h3>How does coulomb conversion differ from other electric charge units?</h3><p>As the SI base unit for electric charge, the coulomb serves as the foundation for all electric charge conversions. All other electric charge units are derived from or related to the coulomb. This relationship makes coulomb conversion particularly straightforward compared to converting between unrelated units.</p></div>
            <div class="faq-item"><h3>Can I convert very small or very large measurements in coulombs?</h3><p>Yes, our coulomb converter handles both extremely small and large measurements with precision. For microscopic work, convert elementary charges to coulombs (1 e ≈ 1.602×10⁻¹⁹ C). For large-scale applications, convert coulombs to ampere-hours (1 Ah = 3600 C). Our smart rounding feature ensures readable results for all scales.</p></div>
            <div class="faq-item"><h3>Is your coulomb conversion tool free to use?</h3><p>Yes, our coulomb conversion calculator is completely free with no registration required. Simply enter your value, select your target unit, and get instant, accurate results. We believe precise measurement conversion should be accessible to everyone, from students learning about electricity to professionals working on complex electrical engineering projects.</p></div>
        </section>
    </div>
</main>

<!-- Inline JavaScript -->
<script>
const chargeUnits = {
    C: 1, Ah: 3600, mAh: 3.6, F: 96485.33212, e: 1.602176634e-19, statcoulomb: 2997924580
};

let decimalPrecision = "Auto";
let decimalPrecision2 = "Auto";

function convertCharge(value, fromUnit, toUnit) {
    return (value * chargeUnits[fromUnit]) / chargeUnits[toUnit];
}

// First converter elements
const input = document.getElementById('chargeValue');
const fromSelect = document.getElementById('fromUnit');
const toSelect = document.getElementById('toUnit');
const resultDiv = document.getElementById('resultValue');
const swapBtn = document.getElementById('swapUnits');
const quickConvertBtns = document.querySelectorAll('.quick-conversions .quick-convert');
const increaseDecimalsBtn = document.getElementById('increaseDecimals');
const decreaseDecimalsBtn = document.getElementById('decreaseDecimals');
const resetBtn = document.getElementById('resetConverter');
const decimalPrecisionSpan = document.getElementById('decimalPrecision');

// Second converter elements
const input2 = document.getElementById('chargeValue2');
const fromSelect2 = document.getElementById('fromUnit2');
const toSelect2 = document.getElementById('toUnit2');
const resultDiv2 = document.getElementById('resultValue2');
const swapBtn2 = document.getElementById('swapUnits2');
const quickConvertBtns2 = document.querySelectorAll('.quick-conversions .quick-convert');
const increaseDecimalsBtn2 = document.getElementById('increaseDecimals2');
const decreaseDecimalsBtn2 = document.getElementById('decreaseDecimals2');
const resetBtn2 = document.getElementById('resetConverter2');
const decimalPrecisionSpan2 = document.getElementById('decimalPrecision2');

function formatResult(value, precision) {
    if (precision === "Auto") {
        // For very large or very small numbers, use exponential notation
        if (Math.abs(value) > 1e10 || (Math.abs(value) < 1e-6 && value !== 0)) {
            return value.toExponential(6);
        }
        // For regular numbers, limit decimal places
        return parseFloat(value.toFixed(10)).toString();
    } else {
        return value.toFixed(precision);
    }
}

function updateResult() {
    const value = parseFloat(input.value);
    if (!isNaN(value)) {
        const result = convertCharge(value, fromSelect.value, toSelect.value);
        resultDiv.textContent = formatResult(result, decimalPrecision);
    } else resultDiv.textContent = 'Result';
}

function updateResult2() {
    const value = parseFloat(input2.value);
    if (!isNaN(value)) {
        const result = convertCharge(value, fromSelect2.value, toSelect2.value);
        resultDiv2.textContent = formatResult(result, decimalPrecision2);
    } else resultDiv2.textContent = 'Result';
}

// Event listeners for first converter
input.addEventListener('input', updateResult);
fromSelect.addEventListener('change', updateResult);
toSelect.addEventListener('change', updateResult);

// Event listeners for second converter
input2.addEventListener('input', updateResult2);
fromSelect2.addEventListener('change', updateResult2);
toSelect2.addEventListener('change', updateResult2);

swapBtn.addEventListener('click', () => {
    const temp = fromSelect.value;
    fromSelect.value = toSelect.value;
    toSelect.value = temp;
    updateResult();
});

swapBtn2.addEventListener('click', () => {
    const temp = fromSelect2.value;
    fromSelect2.value = toSelect2.value;
    toSelect2.value = temp;
    updateResult2();
});

quickConvertBtns.forEach(btn => {
    btn.addEventListener('click', () => {
        input.value = btn.dataset.value;
        updateResult();
    });
});

quickConvertBtns2.forEach(btn => {
    btn.addEventListener('click', () => {
        input2.value = btn.dataset.value;
        updateResult2();
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});

increaseDecimalsBtn.addEventListener('click', () => {
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    updateResult();
});

decreaseDecimalsBtn.addEventListener('click', () => {
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increaseDecimalsBtn2.addEventListener('click', () => {
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    decimalPrecisionSpan2.textContent = decimalPrecision2;
    updateResult2();
});

decreaseDecimalsBtn2.addEventListener('click', () => {
    if (decimalPrecision2 === 0) {
        decimalPrecision2 = "Auto";
    } else if (decimalPrecision2 !== "Auto") {
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    decimalPrecisionSpan2.textContent = decimalPrecision2;
    updateResult2();
});

resetBtn.addEventListener('click', () => {
    input.value = '';
    fromSelect.selectedIndex = 0;
    toSelect.selectedIndex = 0;
    decimalPrecision = "Auto";
    decimalPrecisionSpan.textContent = "Auto";
    resultDiv.textContent = 'Result';
});

resetBtn2.addEventListener('click', () => {
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    decimalPrecision2 = "Auto";
    decimalPrecisionSpan2.textContent = "Auto";
    resultDiv2.textContent = 'Result';
});
</script>