P5-Electric Circuits

Question 1

Describe the forces between objects with
Like charges
Opposite charges

Answer 1

Like charges repel

Opposite charges attract

Question 2

Explain how static electricity can make clothes crackle when you take them off?

Answer 2

Electrons can get pulled off this leaves a static charge on you and an opposite charge on the jumper

Question 3

Explain why electric current can flow in metals

Answer 3

Free electrons can move around

Question 4

Explain what current voltage and resistance are in an electric circuit

Answer 4

Current is the flow of charges around a circuit. It’s measured in amps
Voltage is the driving force that pushes the current around. Units are volts
Resistance is caused by things in the circuit that slow down the flow of change its units ad ohms

Question 5

What happens to the amount of current in a circuit if the voltage of the battery is increased

Answer 5

The bigger the voltage the bigger the current

Question 6

What does the power of an appliance measure

Answer 6

Power is the rate at which an electrical power supply transfers energy to an appliance

Question 7

A remote controlled helicopter has a voltage of 230v and a current of 5 A what is its power rating

Answer 7

230 x 5 =1150

Power = voltage x current

Question 8

What is another name for voltage?

Answer 8

Potential difference

Question 9

Calculate the resistance of a wire if the voltage across it is 12v and current through it is 2.5a

Answer 9

Resistance= voltage\current

12\2.5=4.8

Question 10

Describe how the resistance of an LDR varies with light intensity

Answer 10

In bright light the resistance falls

In darkness the resistance goes up

Question 11

What happens to the voltage when several batteries are added to a series circus

Answer 11

Bigger total voltage

Question 12

What voltage is UK mains electricity supplied at?

Answer 12

230

Question 13

Explain what electromagnetic induction is

Answer 13

You can induce ( create ) a voltage in a conductor by moving a magnet into a coil
Of wire

Question 14

Explain how a generator works

Answer 14

In a generator a magnet or an electromagnet rotates or an electromagnet rotates inside a coil of wire this induces a voltage across the ends of a coil

Question 15

What are the four factors that affect the size of the induced voltage produced by a generator

Answer 15

Add an iron core inside the coil
Increase the strength of the magnetic field
Increase the speed of rotation
Increase the number of turns in a coil

Question 16

What are transformers used for

Answer 16

Transformers are used to change the size of an alternating voltage

Question 17

A current carrying wire runs parallel to the lines of force of a magnetic field. Does the wire feel a force?

Answer 17

Yeah the wires feel a force

Question 18

Where does a wire have to be placed to feel the full force of a magnetic field

Answer 18

To feel the full force the wire has to be at right angles to the lines of force of the magnetic field it’s placed in

Question 19

What part of an electric motor reverses the direction of the current

Answer 19

Commutator

Question 20

Briefly describe three used of electric motors

Answer 20

DVD players
Electric cars
Domestic appliances

Question 21

What causes the build up of static electricity?

Answer 21

Caused by rubbing