electrity

Question 1

how does a fuse protect a circuit?

Answer 1

melts it causing it to be broken

Question 2

effects of voltage increase on temp

Answer 2

causes greater rate of electron collisions causing increase in temp

Question 3

series circuit features

Answer 3

voltage is shared

all elements are connected in a single loop

Question 4

parallel circuit features

Answer 4

switch on/off indecently
if one elements breaks the others still work
more power is available

Question 5

LED

Answer 5

light emitting diode

Question 6

thermistor

Answer 6

semiconductor that changes resistance with temperature

Question 7

Diode

Answer 7

it lets current flow in one direction

Question 8

why does the lamp shine

Answer 8

wire gets hot and gives out light

Question 9

metal filament lamp graph

Answer 9

light bulb heats up
current increases so resistance increases
so there is a lower voltage causing the graph to curve

Question 10

if electrical plug becomes warm?

Answer 10

input power increases

input current increases

Question 11

positively charged or negatively charged which can move

Answer 11

only negatively charged particles can move

they will move from an area of negative charge to an earthed area

Question 12

why is there a spark

Answer 12

there is a potential difference

when the optional difference is high enough electrons jump across

Question 13

how to tell the charge?

Answer 13

bring them close to one another - like charges repel

Question 14

current defo

Answer 14

flow of charge

Question 15

voltage defo

Answer 15

energy transferred per unit charge passed

Question 16

Direct Current

Answer 16

Electric current in a circuit that is in one direction only.

Question 17

Alternating Current

Answer 17

Electric current in a circuit that repeatedly reverses its direction.

Question 18

What does the earth wire protect?

Answer 18

The user

Question 19

Circuit Breaker

Answer 19

An electromagnetic switch that opens and cuts the current off off if too much current passes through it.

Question 20

Why are circuit breakers better than fuses?

Answer 20

They work faster

They can be reset

Question 21

Rubbing a polythene rod with a dry cloth.

Answer 21

Transfers electrons to the surface atoms of rod from the cloth, so the rod becomes negatively charged.

Question 22

Rubbing a perspex rod with a dry cloth..

Answer 22

Transfers electrons from the surface atoms of the rod to the cloth, so the rod becomes positively charged.(loses electrons)

Question 23

Battery.

Answer 23

A cell is necessary to push electrons around a complete circuit. A battery consists of two or more cells.

Question 24

Ammeter.

Answer 24

Used to measure current.

Question 25

Resistor.

Answer 25

Limits the current in a circuit.

Question 26

Variable Resistor.

Answer 26

allows the current to be varied.

Question 27

Explain why only electrons are transferred when objects are charged by friction.

Answer 27

Electrons are located in the outer shells of an atom and are easily removed.

However, protons are located in the nucleus at the centre of the atom and are tightly bound.

Question 28

Explain how a gold leaf electroscope works.

Answer 28

When it is charged, both the rod and leaf adopt the same charge and the gold leaf is repelled from the rod and rises.

The greater the charge, the greater the repulsion the further the gold foil rises.

Question 29

There is a large insulated coil of wire inside the kettle. Explain why this coil of wire gets hot when the kettle is switched on.

Answer 29

MP1. there is a current in
the coil / wire;
MP2. coil / wire has resistance;
MP3. electrical energy transferred to thermal energy;