Chapter 9: Electricity

Question 1

Define electric current.

Answer 1

Electric current is the flow of charge carriers and is measured in ampere.

Question 2

What is the direction of conventional current?

Answer 2

Positive to negative

Question 3

Current is measured using what?

Answer 3

Ammeter

Question 4

Ammeters should always be connected in?

Answer 4

Series

Question 5

Charge of an electron

Answer 5

-1.6*10^-19 C

Question 6

Charge of a proton

Answer 6

1.6*10^-19 C

Question 7

Charge carried by charged particles are known as?

Answer 7

Quantised

Question 8

Formula for current/charge

Answer 8

Q=It

Question 9

Calculating current in a current varying conductor formula

Answer 9

I = Anvq

n = number density of charge carriers (m^-3)

Question 10

Define potential difference across a component in a circuit.

Answer 10

Energy transferred per unit charge flowing from one point to another.

Question 11

Potential difference is measured using a?

Answer 11

Voltmeter

Question 12

Voltmeters must always be placed __ in a circuit

Answer 12

Parallel between 2 points

Question 13

Potential difference/voltage formula

Answer 13

V = W/Q

Question 14

Power formulas (3)

Answer 14

P = IV
P = I^2R
P = V^2/R

Question 15

State ohms law resistance formula

Answer 15

V = IR
R = V/I

Question 16

Resistance is messed in?

Answer 16

Ohms

Question 17

State ohms law

Answer 17

For a conductor at constant temperature (aka constant resistance) the the current through it is proportional to the potential difference across it.

V = IR

Question 18

Current against voltage graph for fixed resistor (metallic conductor) and what does gradient represent. Which is x and which is y axis

Answer 18

Straight line (through origin) and 1/gradient represents resistance

Current is x axis and voltage is y axis

Question 19

IV characteristic/graph for a semi conductor diode

Answer 19

Straight line for half and then curve up

Question 20

IV characteristic/graph for a filament lamp

Answer 20

An s shape

Question 21

As temp increases what happens to resistance (of conductors (metals))

Answer 21

Increases

Question 22

Resistance formula resistivity what it depends on

Answer 22

R = ρL/A

ρ is resistivity is Ωm

Question 23

Resistivity if metals, semi conductors and insulators respectively

Answer 23

Increase; insulators have the highest resistivity.

Question 24

In questions the better conductor will have?

Answer 24

Lower resistance

Question 25

LDR Graph

Answer 25

Light intensity x axis Resistance y axis Decreasing curve

Question 26

Thermistor graph

Answer 26

X axis temperature Y axis resistance Decreasing curve