P3.2 -

Question 1

what is the role of an ammeter?

and where is it positioned in a circuit?

Answer 1

measures current in a circuit

in line with the component - as the current needs to flow THROUGH them

Question 2

what is the role of a voltmeter?

and where is it positioned in a circuit?

Answer 2

measures the difference in voltage between two points

is positioned on both sides of a component - or on another ‘branch’

Question 3

in a series circuit, describe the features of:

a) current
b) potential difference
c) resistance

Answer 3

a) current - is equal across all components
b) total pd is equal to addition of all pds
c) res - of all components is different

Question 4

in a parallel circuit, describe the features of:

a) current
b) potential difference
c) resistance

Answer 4

a) current - split between different branches NOT EQUAL
b) pd across all components are equal
c) res - of all components are different

Question 5

in a symbol of a cell, which one is positive and which is negative?

Answer 5

long one = positive

short one = negative

Question 6

what two factors does current depend on?

Answer 6

resistance

potential difference

Question 7

what is the equation to calculate potential difference?(give units and full words)

Answer 7

V = IR

potential difference (V) = current (A) x resistance (Ω)

Question 8

define potential difference

Answer 8

the difference in voltage between two points

Question 9

what is the difference between a variable resistor and a normal resistor?

Answer 9

a variable resistor’s resistance can change, a normal resistor’s resistance cannot

Question 10

how does a battery cause a current to flow in a circuit?

Answer 10

in a cell, the positive terminal is at a higher electric potential than the negative terminal.

and so there is a POTENTIAL DIFFERENCE in which the electrons move from the higher energy terminal to the other (to balance out)

Question 11

what is the equation to calculate the energy transferred in a circuit?

Answer 11

J = V x Q

energy transferred (J) = potential difference (V) x charge (C)

Question 12

state the factor which allows the transfer energy in a circuit

Answer 12

resistance

Question 13

explain how a hotter wire affects the resistance

Answer 13

• in wire/component, ions usually vibrate up and down
• vibrating ions get more energy so they vibrate faster
• so more electrons collide with the ions

SO MORE RESISTANCE AS MORE ENERGY IS TRANSFERRED BY CURRENT

Question 14

What is VOLTAGE actually?

Answer 14

Voltage is electric potential energy per unit charge, measured in joules per coulomb ( = volts).