# How do electric motors work? - Higher - OCR 21C test questions - OCR 21st Century

### 1

Which of the following is a way of working out which way the force on a current carrying wire will act when in a magnetic field?

### 2

What sort of force is generated when the current and the magnetic field are parallel to each other?

### 3

In Fleming’s left-hand rule, which finger represents the current?

### 4

Which equation is used to calculate the force on a wire carrying a current at right angles to a magnetic field?

### 5

When using Fleming’s left-hand rule, what does the forefinger represent?

### 6

When using Fleming's left-hand rule, what does the thumb represent?

### 7

A 0.1 m length of wire carries a current of 0.4 A in a 0.7 T magnetic field. What force acts on the wire?

### 8

In a dc motor, what is the function of the split ring commutator?

### 9

A 0.1 m length of wire carries a current of 0.02 A in a 5 T magnetic field. What force acts on the wire?

### 10

Considering a current carrying wire in a magnetic field, which of the following graphs is not a straight line passing through the origin?