Electricity

Question 1

Definition of electric current

Answer 1

rate of flow of charge

Question 2

in which direction does current flow?

Answer 2

current always flows from positive to negative. electrons flow the opposite way

Question 3

finding charge given number of electrons, passing through a point

Answer 3

Q = ne (Number of electrons times charge of one electron)

Question 4

finding current given Number of charge carriers passing through a point per second

Answer 4

I = nQ (Number of charge carriers passing through per second times charge of each)

Question 5

Kirchhoff’s first law

Answer 5

Electric charge is conserved in all circuits

Question 6

Kirchhoff’s second law

Answer 6

Energy is conserved in all circuits. for any complete circuit loop, the sum of the EMFs is equal to the sum of the potential differences.

Question 7

components of current, voltage and resistance throughout a circuit in series

Answer 7

Question 8

components of current, voltage and resistance throughout a circuit in parallel

Answer 8

Question 9

Ohm’s law

Answer 9

The potential difference across a conductor is proportional to the current through it, provided the physical conditions do not change

Question 10

using a voltmeter

Answer 10

1) voltmeter must be connected in parallel with component (pd must be same for both)
2) current through voltmeter must be as small as possible (so pd across component not affected)(so voltmeters has very large resistance)

Question 11

using an ammeter

Answer 11

1)ammeter must be connected in series with component (current must be same for both)
2) current through component must not be affected by ammeter. (So ammeters have very low resistance)

Question 12

I-V graph for resistor

Answer 12

Question 13

I-V Graph for filament lamp.

Answer 13

Question 14

I-V Graph for semiconducting diode

Answer 14

Question 15

variable resistor

Answer 15

a resistor whose value can be changed

Question 16

thermistor

Answer 16

resistor whose resistivity varies with temperature (inversely proportional)

Question 17

light dependant resistor (LDR)

Answer 17

resistance varies with light intensity (inversely proportional)

Question 18

graph of resistance agaist temperature for a thermistor

Answer 18

Question 19

graph of resistance against light intensity for LDR

Answer 19

Question 20

What is a diode?

Answer 20

A type of door where the electricity can only move through one way

Question 21

diode in forward bias

Answer 21

Question 22

Superconductor

Answer 22

Wire/device which has 0 resistivity at and below a critical temperature

Question 23

Charge carriers

Answer 23

Charged particles that move through a substance when p.d. Is applied across it

Question 24

P.d.

Answer 24

Work done per unit charge

Question 25

Total current leaving a junction

Answer 25

= total current entering a junction

Question 26

Current of 2 or more in series

Answer 26

The same for each component

Question 27

Total voltage for resistors in series

Answer 27

Sum of p.d. of each individual resistor

Question 28

P.d. for resistors in parallel

Answer 28

The same for each, p.d. entering is not split up

Question 29

Emf

Answer 29

Energy per unit charge

Question 30

I cell

Answer 30

Ecell/total circuit resistance

Question 31

Potential divider

Answer 31

Two or more resistors in series connected to a source of p.d.

Question 32

Emf of multiple cells

Answer 32