Paper 2 - Magnetism and Electromagnetism

Question 1

Describe the construction of electromagnets

Answer 1

• Wire wrapped around an iron nail (iron is a soft magnetic substance)
• A current flows through the wire, creating an electromagnet

Question 2

Draw magnetic field patterns for a straight wire when carrying a current

Answer 2

Draw it then google it

Question 3

draw magnetic field patterns for a flat circular coil when carrying a current

Answer 3

Draw it then google it

Question 4

Draw magnetic field patterns for a solenoid when carrying a current

Answer 4

Draw it then google it

Question 5

When is there a force on a charged particle?

Answer 5

When a charged particle moves in a magnetic
field as long as its motion is not parallel to the field

Question 6

Describe the structure of a transformer

Answer 6

• More coils on one side than the other (to step up/down the voltage)
• Soft iron core containing magnetic field
• Alternating current flowing through wires

Question 7

What does a transformer do and how?

Answer 7

A transformer changes the size of an alternating voltage by having different numbers of turns on the input and output sides

Question 8

Explain the use of a step-up transformer in the large-scale generation and transmission of electrical energy

Answer 8

• Steps up voltage
• To decrease current
• To reduce energy lost as heat to the surroundings
• To transmit electrical energy faster
• To transmit electrical energy over longer distances

Question 9

Explain the use of a step-down transformer in the large-scale generation and transmission of electrical energy

Answer 9

• Steps down voltage to 230V-240V
• To increase current
• To prevent damage to domestic appliances

Question 10

What is the relationship between primary and secondary voltages and the turns ratio for a transformer?

Answer 10

Vp Np
— = —
Vs Ns

Question 11

What is the equation for input power = output power?

Answer 11

Vp Ip = Vs Is

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