P4 Electric circuits

Question 1

What is static electricity?

Answer 1

When you rub two electrically insulating materials together and electrons are rubbed off one material and deposited on the other

Question 2

What is a non-contact force?

Answer 2

A force between two charged objects

Question 3

What is the equation for current?

Answer 3

Current (A) = Charge (C)/time (s)

Question 4

What does a cell do?

Answer 4

Pushes electrons around a complete circuit

Question 5

What does a switch do?

Answer 5

Enables current to be switched on and off

Question 6

What does a bulb do?

Answer 6

Emits light when a current passes through it

Question 7

What does a diode do?

Answer 7

Allows current through in one direction only

Question 8

What does a light emitting diode do?

Answer 8

Emits light when a current passes through it

Question 9

What does an ammeter do?

Answer 9

Used to measure electric current

Question 10

What does a fixed resistor do?

Answer 10

Limits the current in a circuit

Question 11

What does a variable resistor do?

Answer 11

Allows the current to be varied

Question 12

What does a fuse do?

Answer 12

Designed to melt and “break” circuit if the current is greater than a certain amount

Question 13

What does a heater do?

Answer 13

Transfers energy from an electric current to heat up surroundings

Question 14

What does a voltmeter do?

Answer 14

Used to measure potential difference

Question 15

How are voltmeters are always connected with the circuit?

Answer 15

In parallel

Question 16

What is the equation for potential difference?

Answer 16

Potential difference (V) = Energy transferred (J)/Charge (C)

Question 17

What is resistance?

Answer 17

The opposition to current flow

Question 18

What is the equation for resistance?

Answer 18

Resistance (Ohms) = Potential difference (V)/Current (A)

Question 19

What does Ohms law state?

Answer 19

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

Question 20

Explain the relationship between the resistance and current of a filament lamp

Answer 20

As the resistance increases so does the current, because as the resistance increases so does the temperature

Question 21

What is the relationship between resistance and temperature for a thermistor?

Answer 21

The resistance decreases if its temperature increases

Question 22

What is the relationship between resistance and light intensity for a light-dependant resistor?

Answer 22

The resistance decreases as the light falling on it gets brighter

Question 23

What would happen if there was a break at any point in a series circuit?

Answer 23

The charge would stop flowing

Question 24

What is the current in each component in a series circuit?

Answer 24

The same

Question 25

In a series circuit how is the total potential difference distributed?

Answer 25

It is shared between the components

Question 26

How would you find the total resistance in a series circuit?

Answer 26

Adding the resistance of each component

Question 27

What would happen to the resistance if you added more resistors to series circuit?

Answer 27

It would increase the total resistance because the current through the resistors is reduced and the total potential difference across them is unchanged

Question 28

What would happen if there was a break in one of the branches in a parallel circuit?

Answer 28

Charge would still flow in the other parts

Question 29

What is the total current in a parallel circuit?

Answer 29

It is the sum of the currents through separate components

Question 30

What is the potential difference in a parallel circuit?

Answer 30

The same across each component

Question 31

What would happen to the resistance if you added more resistors to parallel circuit?

Answer 31

The resistance would decrease because the total current through the resistors is increased and the total potential difference across them is unchanged