Electricity

Question 1

What is the equation that links Energy,Charge and Voltage

Answer 1

Energy (J) = Charge (C) * Voltage (V)

Question 2

What is the equation that links Energy,Power and Time

Answer 2

Energy (J) = Power (W) * Time (S)

Question 3

What is the Equation that links Power,Voltage and current

Answer 3

Power (W) = Voltage (V) * Current (A)

Question 4

What is the equation that links Power,Current and Resistance

Answer 4

Power (W) = Current² (A) * Resistance (Ω)

Question 5

What is the equation that links Charge,Current and Time

Answer 5

Charge (C) = Current (A) * Time (s)

Question 6

What is the equation that links Voltage,Current and Resistance

Answer 6

Voltage (V) = Current (A) * Resistance (Ω)

Question 7

What is the equation for Efficiency

Answer 7

Efficiency = Useful Power
——————— * 100
Total Input Power

Question 8

What is current

Answer 8

rate of flow of charge

Question 9

What is unit for Charge

Answer 9

Coulombs (C)

Question 10

Define Voltage

Answer 10

Potential Difference- Energy transferred per unit charge

Question 11

What is voltage always proportional to in series

Answer 11

Voltage is always proportional to the current when resistance is contsant (temp. remains constant)

Question 12

What stays the same in series

Answer 12

Same current goes through the cell and resistors in circuit. I Cell. IR = IR2

Question 13

What is shared between resistors in series

Answer 13

Voltage is shared between resistors. Vcell = VR1 + VR2

Question 14

How is current calculated in series

Answer 14

Current = Total Voltage / Total Resistance

Question 15

How is proportionate share of voltage calculated in series

Answer 15

Resistance of compound/total resistance = proportionate share of voltage

Question 16

What stays the same in parallel circuits

Answer 16

Voltage stays the same. Vcell = V1 + V2

Question 17

What happens to current in parallel circuits

Answer 17

Current splits in parallel circuits so I0 = I1 + i2

Question 18

How is current calculated

Answer 18

I1 = Vcell/R1

Question 19

What is the relationship between resistance and light in a LDR

Answer 19

Resistance decreases as light intensity increases, non-linear

Question 20

What is the relationship between resistance and temperature in a thermistor

Answer 20

Resistance of a thermistor decreases, as temp. increases. Non-Linear

Question 21

What is the quality of an ohmic conductor

Answer 21

Current is directly proportional to the voltage running through it

Question 22

Why is current and voltage not proportional in a non-ohmic conductor

Answer 22

As voltage inc., current inc. , so temp. inc causing resistance to inc.

Question 23

What is the forward direction of a diode and led

Answer 23

——->—- (right is forward). it doesn’t work in the reversal direction

Question 24

What is direct current

Answer 24

current in one direction only

Question 25

what is alternating current

Answer 25

current repeatedly reverses its direction. UK mains is this

Question 26

In which direction does current flow

Answer 26

Positive to negative (anticlockwise)

Question 27

What is the frequency of the UK Mains circuit

Answer 27

50Hz

Question 28

What is the peak voltage of the Uk Mains

Answer 28

325V

Question 29

What is the average Voltage of the Uk mains

Answer 29

230V

Question 30

What is the time period of the Uk mains

Answer 30

0.02 s

Question 31

Name three factors that affect the resistance of metals (at a constant temp.)

Answer 31

- Type of Metal - Length of Metal (Longer Wire,higher resistance) - Thickness of Metal (thinner wire,higher resistance)

Question 32

What material are electrical cables made out of

Answer 32

Copper

Question 33

What are the wires encased in

Answer 33

plastic as it is an electrical insulator

Question 34

What 3 wires do the cable contain and what colours are each

Answer 34

- Earth = Green/Yellow - Live=Brown - Neutral=Blue

Question 35

What is the purpose of the Live Wire

Answer 35

It contains the AC Current

Question 36

What is the purpose of the Neutral Wire

Answer 36

It stays at zero and completes the circuit

Question 37

What is the purpose of the Earth Wire

Answer 37

It connects the appliance case to the earth so if an accident occurs a very large current overloads to the earth and blows the fuse

Question 38

What is the purpose of a fuse

Answer 38

If the current exceeds the limit the fuse melts and stops the circuit

Question 39

what can only move in static electricity

Answer 39

only electrons

Question 40

What can electrons do in conductors

Answer 40

electrons can move across the object giving negative charge (induced charge)

Question 41

What can electrons do in insulators

Answer 41

electrons can move to one side of the atom

Question 42

How can objects be charged

Answer 42

They can be charged by friction