Electromotive force (E.M.F) and potential difference are fundamental concepts in electrical circuits. E.M.F refers to the energy supplied by a source, such as a battery or generator, per unit charge as it moves through the circuit, effectively driving the flow of electric current. It is measured in volts and represents the maximum potential difference the source can provide when no current is flowing. In contrast, potential difference (often simply called voltage) is the difference in electric potential between two points in a circuit when current is flowing. It indicates the work done to move a unit charge from one point to another and is also measured in volts. While E.M.F is associated with the energy supplied by the source, potential difference reflects the energy lost or gained by charges as they move through circuit elements, such as resistors.
What is Electromotive Force (E.M.F)?
E.M.F is the energy supplied by a source, such as a battery or generator, per unit charge as it moves through the circuit, driving the flow of electric current.
How is E.M.F measured?
E.M.F is measured in volts (V), which quantifies the energy provided to each unit of electric charge.
What is the difference between E.M.F and potential difference?
E.M.F refers to the energy supplied by a source when no current is flowing, while potential difference is the energy difference between two points in a circuit when current is flowing.
What happens to the potential difference across a resistor when current flows through it?
The potential difference across a resistor represents the energy lost by the charge as it passes through the resistor, and it is equal to the product of the current and the resistance (Ohm's Law: V = I×R).
Can E.M.F exist without a current flowing in the circuit?
Yes, E.M.F can exist without current flowing; it represents the maximum potential difference the source can provide when the circuit is open.
What does E.M.F stand for?
a) Electromagnetic Force
b) Electromotive Force
c) Electric Motor Force
d) Electromagnetic Field
Answer: b) Electromotive Force
Which unit is used to measure E.M.F?
a) Amperes
b) Ohms
c) Volts
d) Watts
Answer: c) Volts
What is the primary function of E.M.F in a circuit?
a) To measure current
b) To provide energy to move charges
c) To increase resistance
d) To decrease voltage
Answer: b) To provide energy to move charges
What is the relationship between potential difference (V), E.M.F (E), and internal resistance (r) in a circuit?
a) V = E + I × r
b) V = E - I × r
c) V = I × r
d) V = E × I
Answer: b) V = E - I × r
When is the potential difference across a battery equal to its E.M.F?
a) When the circuit is open
b) When the circuit is shorted
c) When no current is flowing
d) When the battery is fully charged
Answer: c) When no current is flowing