Mock

Question 1

Size of atom?

Answer 1

_10
1x10 0.1 nm

Question 2

Specific latent heat

what is Fusion and Vaporisation?

Answer 2

Fusion- melting/ freezing

Vaporisation- evaporating/ condensing

Question 3

What is a nanometre

Answer 3

_9
1m x 10

Question 4

What is the unit for specific latent heat

Answer 4

J / kg

Question 5

What is specific latent heat

Answer 5

The amount of energy required to change the state of a 1kg substance without any change in temperature.

Question 6

All quantities can be measured by one of two types: scalars and vectors

What are they (give example)

Answer 6

Scalar- quantities that have only a magnitude (E.g. mass)

Vector- quantities that have both magnitude and direction (E.g. velocity)

Question 7

How to find the speed on a distance time graph?

Answer 7

Rise
——
Run

Question 8

On a velocity time graph what does a straight line represent?

Answer 8

Constant acceleration

Question 9

On a velocity time graph what does a flat line represent?

Answer 9

Constant velocity

Question 10

How to calculate acceleration on a velocity time graph?

Answer 10

Change in velocity
_____________________
Change in time

(grad of line)

Question 11

What is acceleration measured in?

Answer 11

2
m/ s

Question 12

What does the area under a velocity time graph represent?

Answer 12

The displacement (distance travelled)

Question 13

Acceleration equation #2

Answer 13

Change in velocity
————————
Time. Taken

Question 14

In a parallel circuit, what do voltage and current do?

Answer 14

Voltage across each component is the same

Current splits up between branches

Question 15

In a series circuit what do current and voltage do?

Answer 15

Current stays the same throughout

Voltage is shared between components

Question 16

In a series circuit what do voltage and current do?

Answer 16

Voltage is shared between components

Current stats the same throughout

Question 17

What is conventional current?

Answer 17

The flow of positive charge (opposite of current)

Question 18

What is power measured in

Answer 18

Watts

Question 19

Equation for current

Answer 19

Current = charge / time

Question 20

Equation for resistance

Answer 20

Resistance= potential difference/ current

Question 21

In Flemming’s left hand rule what do thumbs, first finger and second finger represent?

Answer 21

Thumb- thrust

First finger- field

Second finger- current

Question 22

Describe a simple d.c motor

Answer 22

The simple d.c. motor consists of a coil of wire (which is free to rotate) positioned in a uniform magnetic field

• The coil of wire, when horizontal, forms a complete circuit with a cell

• The coil is attached to a split ring (a circular tube of metal split in two)

• This split ring is connected in a circuit with the cell via contact with conducting carbon brushes

Question 23

Explain EMI

(Electromagnetic induction)

Answer 23

If there is a relative movement between a conductor and a magnetic field a potential difference will be induced

This is because the conductor cuts through the magnetic field lines

Or you can move a magnetic field through a fixed conductor such as a coil which induced a potential difference in the coil

There must be a relative movement or ‘motion’ for EMI to occur

Question 24

Direct current is generated in a …?

Answer 24

Dynamo

Question 25

Difference between a dynamo and an alternator?

Answer 25

A simple dynamo is the same as an alternator except that the dynamo has a split ring commutator instead of two separate slip rings.

Question 26

Motor vs Generator

Answer 26

A motor takes in electricity and turns it into motion. A generator takes in motion and generates electricity

Question 27

The transformer equation

Answer 27

V across prim coil N° turns on prim coil ———————— = ————————— V across sec coil N° turns on sec coil Vp Np — = — Vs Ns

Question 28

Explain loudspeaksers

Answer 28

Convert electrical signals into sound They consist of a coil of wire which is wrapped around one pole of a permanent magnet. An a.c passes through the coil and creates a magnetic field around the coil. This magnetic field interacts with the field from the permanent magnet, exerting a force on the coil. Because the coil will constantly change direction, it oscillates causing the speaker cone to oscillate creating sound waves.

Question 29

Explain microphones

Answer 29

They convert the pressure variations in sound waves into variations in current. Similar to EMI When sound waves reach the microphone, the pressure variations cause the diaphragm to vibrate causing the coil (which is attached) to move back and forth through the magnetic field. The coil cuts through the field lines inducing an a.c

Question 30

Equation using current, resistance and voltage

Answer 30

Current = voltage / resistance