P3

Question 1

What happens when two insulators are rubbed together?

Answer 1

Electrons are transferred from one insulator to another
The positive charges don’t move so one insulator ends up with extra electrons and one with not enough

Question 2

What are sparks?

Answer 2

Flows of charge, or a current through the air

Question 3

Where are electrical fields from?

Answer 3

Around charged objects or particles
If another object is in the field it will either be attracted or repelled

Question 4

How do you know the strength of a magnetic field?

Answer 4

Stronger field = field lines closer together
Field line always go to the positive charge

Question 5

What is current?

Answer 5

Rate of flow of charged particles, or charge

Question 6

How do you calculate charge flow?

Answer 6

Change flow (C) = current x time

Question 7

What is potential difference?

Answer 7

Measured in volts
Push needed to get the charges from one point to another (make a current flow)

Question 8

What is the equation for energy transferred?

Answer 8

Energy transferred = p.d x charge

Question 9

What is a series circuit?

Answer 9

Only has one loop
Current is the same everywhere
P.d divides proportional to the resistors

Question 10

Where do the voltmeter and ammeter go in a series circuit?

Answer 10

Ammeter goes in series
Voltmeter connected to both sides if a component and parallel

Question 11

What happens in a parallel circuit?

Answer 11

Has multiple loops
Each loops works independently
The current at different points will add to the current near the battery
P.d is the same at each path

Question 12

What does current depend on?

Answer 12

Potential difference of the cell or the battery
Resistance of components

Question 13

What is resistance?

Answer 13

Measured in ohms
Opposition to current
Tells the circuit how much current flows for a given p.d.
Insulators have a high resistance (no current flows)

Question 14

What is the equation for resistance?

Answer 14

Resistance = p.d (V)/current(I)

Question 15

How to find net resistance?

Answer 15

1/R1 + 1/R2 = 1/net resistance
Do reciprocal

Question 16

What is a variable resistor?

Answer 16

Circuit component used to change the quantity of wire or other resisting material

Question 17

What is a characteristic graph?

Answer 17

A graph of current against p.d.

Question 18

What is the characteristic graph for a resistance wire or fixed resistor?

Answer 18

Constant linear resistance
Straight line through the origin (obeys Ohms law, current is directly proportional to p.d)

Question 19

What is the characteristic graph for a filament lamp?

Answer 19

Resistance increases when the current gets bigger as the filament lamp gets hotter (ions in the metal lattice vintage more and moving electrons collide more frequently)
Non linear circuit element

Question 20

What is a diode?

Answer 20

Component that only allows current to flow in way
LED (light emitting diode)

Question 21

What is the characteristic graph for a diode?

Answer 21

Current remains zero until p.d. = 0.6V then suddenly current increases as resistance decreases

Question 22

What is a thermistor?

Answer 22

Component whose resistance decrease with an increase of temperature
Inveresly proportional
Monitor temperature (of ovens, laptoposnto prevent overheating)

Question 23

What is LDR?

Answer 23

Changes with light intensity
Component whose resistance decreases with greater light levels
When it is darker the resistance is high
Same shape graph as thermistors

Question 24

What is electrical power?

Answer 24

Rate at which energy is transferred

Question 25

Equation for electrical power?

Answer 25

P = IV
P = IR^2