Chap 12 - 14

Question 1

Law of electrostatics

Answer 1

Unlike charges attract, like charges repel

Question 2

Conductors vs Insulators of electricity

Answer 2

Conductors have free moving electrons while insulators do not

Question 3

What is current

Answer 3

Current is the rate of flow of electric charge

Question 4

Charge fomula

Answer 4

Q = iT
Charge(C) = Current(A) * time(s)

Question 5

conventional current flow vs electron flow

Answer 5

conventional flow - positive to negative
electron flow - negative to positive

Question 6

Voltage formula

Answer 6

V=W/Q
P.d.(V) or e.m.f(V) = Work done(J)or energy(J) /Charge(C)

Question 7

Resistance fomula

Answer 7

R = V/I
resistance = voltage/current

Question 8

resistance of a wire formula

Answer 8

R= p(l/A)
resistance = resistivity (length/area)

Question 9

In a series circuit, what is the properties of charge, voltage/emf and resistance

Answer 9

I(charge) = I1 = I2 = I3
V(volt/emf) = V1 + V2 + V3
R(resistance) = R1 + R2 + R3

Question 10

In a parallel circuit, what is the properties of charge, voltage/emf and resistance

Answer 10

I(charge) = I1 + I2 + I3
V(volt/emf) = V1 = V2 = V3
R(resistance) = (1/R1 + 1/R2 + 1/R3)^-1

Question 11

Power formula

Answer 11

P = IV
OR
P=I²R
OR
P=V²/R

Question 12

Energy formula

Answer 12

E=P(ower)t
OR
E=VIt
OR
E=V²/R
OR
E=I²Rt

Question 13

Cost of electricity used

Answer 13

kWh * cost for 1kWh

Question 14

Dangers of Electricity

Answer 14

Exposed wires
Overheating cables
Damp conditions

Question 15

What colour is the
Earth wire
Live wire
Neutral wire

Answer 15

Earth wire: Yellow with Green stripes
Live wire: Brown
Neutral wire: Blue

Question 16

What is the use of Earth Wire

Answer 16

If live wire touches the casing, the earth wire will help redirect the current towards the earth so that the casing is not ‘live’. Thus protecting the user

Question 17

What is the use of a fuse.

Answer 17

If current exceeds fuse rating, the fuse melts and opens the circuits. Current stops flowing.