Electromagnetism: Potential Difference and EMF

Potential difference is the work done in moving a charge of one coulomb from one point to another and its SI unit is the volt (V).

Work is done to overcome the force of repulsion between the two positive charges.

The work done is calculated using the formula W = QV.

<p>Zero potential refers to a condition where no work is done when charges are at infinite distances apart, commonly associated with the earth.</p> Signup and view all the answers

<p>The potential of the conductor is brought to zero when it is connected to the earth.</p> Signup and view all the answers

<p>All points on a conductor carrying a static charge must be at the same potential.</p> Signup and view all the answers

<p>Potential difference is measured using a voltmeter connected in parallel with the component.</p> Signup and view all the answers

<p>Electromotive force (emf) represents the energy supplied per coulomb of charge passing through a circuit.</p> Signup and view all the answers

<p>The work done is 60 J, calculated using W = QV → W = 5 C × 12 V.</p> Signup and view all the answers

<p>Potential difference describes the energy used by one coulomb of charge, while emf describes the energy supplied per coulomb.</p> Signup and view all the answers

<p>The emf represents the energy supplied to each coulomb of charge by the power supply.</p> Signup and view all the answers

<p>Charge will move towards the point of lower potential.</p> Signup and view all the answers

<p>A primary cell converts chemical energy into electrical energy and is not rechargeable.</p> Signup and view all the answers

<p>In a simple cell, zinc releases electrons and becomes negative, while copper gains electrons, becoming positive.</p> Signup and view all the answers

<p>A dry battery typically outputs voltages of 3 V, 4.5 V, 6 V, etc.</p> Signup and view all the answers

<p>Secondary cells, like lithium-ion batteries, are rechargeable, while primary cells are not.</p> Signup and view all the answers

<p>Capacitance is directly proportional to charge and inversely proportional to the potential difference, expressed as $C = \frac{Q}{V}$.</p> Signup and view all the answers

<p>Capacitance is affected by the plate area, distance between the plates, and the permittivity of the dielectric material.</p> Signup and view all the answers

<p>Breakdown occurs when the electric field exceeds the dielectric's insulating ability, causing rapid discharge.</p> Signup and view all the answers

<p>The presence of a negatively charged plate reduces the potential of the positively charged conductor.</p> Signup and view all the answers

<p>The capacitance is calculated using the formula $C = \frac{A\epsilon}{d}$.</p> Signup and view all the answers

<p>Increasing the area of the plates increases the capacitance.</p> Signup and view all the answers

<p>Electrons flow onto one plate and off the other, creating a potential difference until the capacitor is fully charged.</p> Signup and view all the answers

<p>The charge is $Q = CV = 4 \times 10^{-6} \times 3 \times 10^{3} = 1.2 \times 10^{-2}$ C.</p> Signup and view all the answers

<p>Reducing the distance increases the capacitance.</p> Signup and view all the answers

<p>When a charged capacitor is connected in a circuit with a bulb, the stored energy discharges, lighting the bulb.</p> Signup and view all the answers

<p>It uses an array of capacitors that reacts to changes in capacitance when a finger or stylus is applied.</p> Signup and view all the answers

<p>The inductor resists current changes, helping to stabilize the current flowing from the capacitor.</p> Signup and view all the answers

<p>Capacitors store charge and can charge/discharge with AC while preventing steady DC from flowing.</p> Signup and view all the answers

<p>The capacitance decreases because capacitance is directly proportional to the area.</p> Signup and view all the answers

<p>The energy stored is $U = \frac{1}{2} C V^2 = \frac{1}{2} (5 \times 10^{-6} , F)(20 , V)^2 = 0.002$ J or 2 mJ.</p> Signup and view all the answers

<p>The charge stored is $Q = CV = (5 \times 10^{-6} , F)(120 , V) = 6 \times 10^{-4}$ C or 600 μC.</p> Signup and view all the answers

<p>Using the formula $C = \frac{\varepsilon A}{d}$, the area is $A = C \cdot \frac{d}{\varepsilon} = 5 \times 10^{-12} \cdot \frac{0.02}{8.85 \times 10^{-12}} \approx 1.13 \times 10^{-3} , m^2$.</p> Signup and view all the answers

<p>Potential difference is the work done per unit charge in moving a charge between two points in an electric field.</p> Signup and view all the answers

<p>Capacitance is the ability of a system to store charge per unit potential difference, given by $C = \frac{Q}{V}$.</p> Signup and view all the answers

<p>The energy stored is $U = \frac{1}{2} (64 \times 10^{-6} , F)(2500 , V)^2 = 200$ J.</p> Signup and view all the answers

<p>Factors include the plate area, the distance between the plates, and the type of dielectric material between the plates.</p> Signup and view all the answers

<p>Using $C = \frac{\varepsilon A}{d}$, the capacitance is $C = \frac{(8.85 \times 10^{-12} , F/m)(40 \times 10^{-4} , m^2)}{0.01 , m} = 3.54 \times 10^{-12}$ F or 3.54 pF.</p> Signup and view all the answers

<p>The net charge is $Q = CV = (3.54 \times 10^{-12} , F)(12 , V) = 4.25 \times 10^{-11}$ C or 42.5 nC.</p> Signup and view all the answers

<p>You can charge a capacitor and then disconnect it from the power source, using it to light a bulb briefly, demonstrating energy release.</p> Signup and view all the answers

<p>A voltmeter is connected in parallel with the component across which the potential difference is to be measured. It displays the voltage across the component by measuring the difference in electric potential.</p> Signup and view all the answers

<p>The work done in moving a charge is directly proportional to the potential difference and the amount of charge transferred, as expressed in the equation $W = QV$. Thus, increasing either the potential difference or the transferred charge results in more work done.</p> Signup and view all the answers

<p>Zero potential occurs when charges are very far apart, resulting in no force or work being done on them. For practical purposes, the earth is considered to have zero potential, providing a reference point for other potentials.</p> Signup and view all the answers

<p>Charge will move from the point of higher potential to the point of lower potential when a potential difference exists. This movement is driven by the electric field created by the potential difference.</p> Signup and view all the answers

<p>Electromotive force (emf) represents the energy provided per coulomb of charge by a power supply, indicating how much energy is available for each coulomb as it moves through the circuit. It is measured in volts.</p> Signup and view all the answers

<p>A dry cell generates electricity through a chemical reaction between its zinc and carbon electrodes, typically providing an output of 1.5 V.</p> Signup and view all the answers

<p>Permittivity measures a material's ability to permit electric field lines, and higher permittivity values increase the capacitance of the capacitor.</p> Signup and view all the answers

<p>As the potential difference across a capacitor increases, the capacitance remains constant, but charge accumulation increases according to the formula $Q=CV$.</p> Signup and view all the answers

<p>The potential of the positively charged conductor decreases, allowing more positive charge to be added without significantly increasing potential.</p> Signup and view all the answers

<p>A lead-acid car battery functions as a secondary cell converting chemical energy into electrical energy and is recharged using the car’s alternator.</p> Signup and view all the answers