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Question 1

What is meant by potential difference?

Answer 1

The energy transferred to a component per coulomb of charge that passes through it

The unit of potential difference is the volt (V)

Question 2

How is potential difference calculated?

Answer 2

V = E/Q

Where E is energy in joules (J) and Q is charge in coulombs (C)

Question 3

What is the formula for resistance?

Answer 3

R = V/I

Where R is resistance in ohms (Ω), V is potential difference in volts (V), and I is current in amperes (A)

Question 4

What does Ohm’s law state?

Answer 4

The current through a resistor at constant temperature is directly proportional to the potential difference across the resistor

This means that resistance remains constant as current changes, provided temperature is constant

Question 5

What is the unit of resistance?

Answer 5

Ohm (Ω)

Question 6

What happens to resistance if the potential difference across a resistor is increased?

Answer 6

Resistance remains constant if the temperature is constant

This is applicable for ohmic conductors

Question 7

Fill in the blank: The unit of potential difference is _______.

Answer 7

volt (V)

Question 8

How does an ammeter function in a circuit?

Answer 8

It measures the current through a component and is connected in series

The ammeter reading indicates current in amperes (A) or milliamperes (mA)

Question 9

How does a voltmeter function in a circuit?

Answer 9

It measures the potential difference across a component and is connected in parallel

The voltmeter reading indicates potential difference in volts (V)

Question 10

What happens to the current when resistance increases for a given potential difference?

Answer 10

The current decreases

Question 11

What is the relationship between current and potential difference in a wire?

Answer 11

They are directly proportional

This relationship is depicted in a current-potential difference graph as a straight line through the origin

Question 12

What does reversing the potential difference across a resistor do?

Answer 12

It reverses the current through the resistor

Question 13

Fill in the blank: The gradient of a current-potential difference graph depends on the _______ of the resistor.

Answer 13

resistance

Question 14

What is the formula for calculating potential difference across a component?

Answer 14

V = E/Q

Question 15

If the current through a wire is 0.5 A and the potential difference is 4.0 V, what is the resistance?

Answer 15

8 Ω

Using the formula R = V/I

Question 16

What is the charge passing through a component if the current is 0.015 A for 1200 seconds?

Answer 16

18 C

Charge (Q) can be calculated using Q = I × t

Question 17

What does a straight line through the origin on a current-potential difference graph indicate?

Answer 17

That the resistance is constant

Question 18

What happens to the resistance of a wire as its length increases?

Answer 18

Resistance increases

This relationship can be investigated by plotting resistance against length