Current and Voltage in Circuits

Question 1

Describe a series circuit

Answer 1

1. There is only one path for the charges to flow along
2. One switch can turn all the components on or off
3. Current is the same and so it doesn’t matter where the ammeter is
4. Voltage (P.D) splits up, the sum of the potential differences across components adds up to the total of the cell/battery, the P.D of each component is not necessarily equal, depends on the resistance of the component. If a component has a larger resistance it gets a bigger ‘share’ of the voltage
5. The more components, the larger the resistance, the lower the current
   - E.G. Xmas tree lights usually in series as only a small low voltage bulbs can be used

Question 2

Describe a parallel circuit

Answer 2

1. There are branches and junctions so the charge can flow in different paths
2. Switch can be placed at different parts to switch bulbs on and off individually or together
3. Voltage is the same across each branch
4. Current splits up, the sum of currents on each branch is equal to the current drawn from power supply/ battery, the current on each branch is not necessarily equal and it depends of the resistance of branch
5. If more bulbs are added to a circuit (in parallel) they all stay bright as each branch of the circuit receives the same amount of voltage (but if in same branch no)
   E.G. Domestic lighting is often connected in parallel

Question 3

How do you connect an ammeter?

Answer 3

In series

Question 4

How do you connect a voltmeter?

Answer 4

In parallel as it measures the difference in voltage across a component (before and after) hence measure the potential difference between a and b

Question 5

What is current?

Answer 5

The rate of the flow of charge

Question 6

What is an advantage and disadvantage of using a series circuit?

Answer 6

Adv: There is a single switch and independent control
Dis: If one component breaks this causes a gap and so the whole circuit stops

Question 7

What is an advantage and disadvantage of using a parallel circuit?

Answer 7

Adv: If one component in a branch breaks, only others in the same branch will be affected, not the whole circuit
Dis:

Question 8

How do you work out charge?

Answer 8

Charge = current x time
Q = It
Coulombs = A x s

Question 9

What is an electrical current in a solid metallic conductor?

Answer 9

• Is a flow of negatively charged electrons
• The electrons flow from the negative terminal of the battery/power supply (from which they are repelled) and then flow to the positive terminal (to which they are attracted)
• However arrow point in the direction of conventional current that goes in the opposite direction (historical accident)

Question 10

What happens to the current if you increase the voltage?

Answer 10

It increases (increasing the voltage, more current will flow)

Question 11

What dies the current in a series circuit depend on?

Answer 11

The applied voltage and the number and nature of other components