Describe how the students could build an electromagnet. Include in your answer how the students should vary and test the strength of their electromagnet.

Question 1

make an electromagnet
• wrap the wire around the nail
• connect the wire to the power supply (with
connecting leads and croc clips)
vary the strength of the electromagnet
• change the number of turns (on the coil) • change the current (through the coil)
test the electromagnet
• suspend paperclips from the electromagnet
• the more paperclips suspended, the stronger the
electromagnet is
• clamp the electromagnet at different distances from
the paperclip(s)
• the further the distance which paperclips can be attracted the stronger the electromagnet is

Question 2

Electric Charge

Answer 2

Electrical current is the flow of electric charges. For an electric charge to flow there are two essential factors:

Potential difference.
Closed (or complete) circuit.

Answer 3

Electric current is measured in amperes (A). A current has the same value at every point in a single closed loop.

Question 4

Give two essential factors for electric charge to flow:

Answer 4

Potential difference

Closed circuit

Answer 5

Current is used in the following equation for calculating the flow of charge:

Flow of charge (C) = current (A) x time (s)
The equation is also written as:

Q = It

Question 6

What unit is electric current measured in?

Answer 6

Amperes

Answer 7

Potential difference is the difference in the amount of energy that charge carriers have between two points in a circuit.

The energy is transferred to the electrical components in a circuit when the charge carriers pass through them.

Question 8

Charge

Answer 8

Charge= current * time

Question 9

10 A of current flow through a wire for 2 seconds. What is the total charge transferred?

Answer 9

1
Remember the equation for charge
Q = It
2
Substitute values
Q = 10 × 2
3
Calculate and remember the unit
Q = 20 C

Question 10

POTENTIAL DIFFERENCE

Answer 10

Potential difference is measured in volts (V) and is also called voltage. Potential difference can be calculated in the following equation:

Potential difference (V) = current (A) × resistance (Ω)
V = IR

Question 11

What is potential difference?

Answer 11

The difference between the amount of energy between 2 points in a circuit

Question 12

VOLT METERS

Answer 12

Voltmeters measure the potential difference (or voltage) between two points in a circuit.

Voltmeters must always be connected in parallel (on a separate branch of the circuit) with the two points being measured.

Question 13

What is the symbol equation for calculating potential difference?

Answer 13

V=IR

Question 14

VOLTMETER

Answer 14

MUST ALWAYS BE CONNECTED IN A PARRALLEL

MEASURE POTENTIAL DIFFERENCE

Question 15

SERIES CIRCUITS

Question 16

A series circuit has all its components connected on the same line as each other.

Answer 16

ONE CONTINIOUS LOOP

Answer 17

In a series circuit, the current is the same at all points in the circuit.

Question 18

How is a resistor drawn in a circuit diagram?

Answer 18

A box with a line on either side

Answer 19

The charge flows through the circuit like water flows through pipes.

The amount of water entering one end of a pipe is the same as the amount leaving the other end.

Question 20

If the current at R1 in a series circuit is 5 A, what is the current at R2 in the same series circuit?

Answer 20

5A

Answer 21

In series circuits, the resistors all oppose the flow of electric current through the circuit.

Question 22

The total resistance in a series circuit is calculated by adding up the resistance of each individual resistor.

Answer 22

E.g. R = R1 + R2 + R3

Question 23

What is the role of resistors in a series circuit?

Answer 23

Oppose the flow of electric current

Question 24

How is a bettery madE?

Answer 24

A battery is made by joining cells together.

Question 25

In a series circuit, R1 = 1 Ω and R2 = 1 Ω. What is the total resistance?

Answer 25

2

Answer 26

The total e.m.f. (energy that drives a current to flow through a circuit) in a series circuit is found by adding up individual electromotive forces (e.m.f) of the cells in the circuit.
E.g. E = E1 + E2 + E3