Parallel and Series Circuits

Question 1

What happens when insulating materials are rubbed together?

Answer 1

Electrons are scraped off one and dumped on the other.

Question 2

When a duster is rubbed on a polythene rod, which way do the electrons move?

Answer 2

From the duster to the rod.

With a Polythene rod, the duster becomes Positive

Question 3

When a duster is rubbed on an acetate rod, which way do the electrons move?

Answer 3

From the rod to the duster.

Question 4

What are positive static charges caused by?

Answer 4

Electrons moving away.

Question 5

What are conductors?

Answer 5

Materials which charges can easily pass through.

Question 6

How does resistance affect current?

Answer 6

The greater the resistance, the smaller the current.

Question 7

What is current?

Answer 7

The rate of flow of charge.

Question 8

What is current measured in?

Answer 8

Amperes (A)

Question 9

What is the formula that connects charge, time and current?

Answer 9

Charge = Current / Time
A = C / s

Question 10

What is potential difference?

Answer 10

Work done per unit charge.

Question 11

What is potential difference measured in?

Answer 11

Volts (V)

Question 12

What is the formula that connects potential difference, charge and work done?

Answer 12

P.D = Work done / Charge
V = J / C

Question 13

Where can ammeters be placed?

Answer 13

Anywhere in series.

Question 14

Where can voltmeters be placed?

Answer 14

In parallel across the component under test.

Question 15

What do variable resistors control?

Answer 15

The current flowing through the circuit.

Question 16

Describe the graph for resistors.

Answer 16

Directly proportional to P.D.

Question 17

Describe the graph for a filament lamp.

Answer 17

As the temperature of the filament increases, the resistance increases.

Question 18

Describe the graph for a diode.

Answer 18

Current only flows in one direction, so resistance is very high in the other direction.

Question 19

Why does resistance increase with temperature?

Answer 19

1. Heat energy causes the ions in the conductor to vibrate more
2. Harder for charge-carrying conductors to get through

Question 20

What formula connects potential difference, current and resistance?

Answer 20

P.D = Current x Resistance
V = I x R

Question 21

What is a diode used for?

Answer 21

To regulate the potential difference in circuits.

Question 22

When do LEDs emit light?

Answer 22

When current flows through in the forward direction.

Question 23

What is an LDR?

Answer 23

Resistors that depend on light intensity.

Question 24

When is resistance highest for an LDR?

Answer 24

In darkness.

Question 25

What is a thermistor?

Answer 25

A temperature dependent resistor.

Question 26

When is resistance highest for a thermistor?

Answer 26

Cool conditions.

Question 27

What happens to potential difference in series circuits?

Answer 27

The voltages around the circuit add up to the source voltage.

Question 28

What happens to current in series circuits?

Answer 28

The same current flows through all parts of the circuit.

Question 29

What happens to resistance in series circuits?

Answer 29

The total resistance is the sum of all the resistances.

Question 30

What happens to cell voltages in series circuits?

Answer 30

They add up.

Question 31

What happens to potential difference in parallel circuits?

Answer 31

The voltage is the same across all components.

Question 32

What happens to current in parallel circuits?

Answer 32

The total current flowing around the circuit is equal to the total of all the currents through the separate components.