Electricity

Question 1

Q=

Answer 1

IT
eN (e x number of electrons)
E/V

Question 2

W (E) =

Answer 2

ItV
QV

Question 3

Ammeter in circuit

Answer 3

-No resistance
-in series

Question 4

Voltmeter in circuit

Answer 4

-Infinite resistance
-parallel

Question 5

Ohm’s law

Answer 5

For a metallic conductor, the current through it is proportional to the potential difference across it, when other variables such as temperature remain constant.a

Question 6

Threshold voltage

Answer 6

When V is less than the threshold voltage, the current of the LED is zero/ very small

Question 7

ρ=

Answer 7

RA/L

Question 8

R=

Answer 8

ρL/A

Question 9

Superconductor

Answer 9

A material that has 0 resistance under a threshold temperature

Question 10

Kirchhoff’s 1st law

Answer 10

Sum of currents entering a junction= sum of currents exiting junction. Total sum=0

Question 11

Kirchhoff’s second law

Answer 11

In any closed loop the sum of emfs= total change in p.d. (Conservation of energy)

Question 12

Emf definition

Answer 12

The electrical energy per unit charge supplied by the battery (chemical->electrical)

Question 13

Potential Difference definition

Answer 13

Work done/Energy transferred per unit charge

Question 14

Resistors in series

Answer 14

Vt= V1+V2+…+Vn
I= constant
Rt= R1+R2+…Rn

Question 15

Resistors in parallel

Answer 15

V= constant
It=I1+I2+…In
1/Rt=1/R1+1/R2+..1/Rn

Question 16

P.d. Across R2 in potential divider circuit

Answer 16

V2= V(in)/(R1+R2)xR2

Question 17

Cells in parallel

Answer 17

Et=E1=E2=…=En
(Identical cells)
rt=r/n