Circuits and Static electricity

Question 1

What is current?

Answer 1

a rate of flow of charge

Question 2

What is resistance?

Answer 2

a measure of how easy or difficult it is for the current to flow

Question 3

What is charge?

Answer 3

A property of matter that causes it to be positive or negative.

Question 4

What is potential difference?

Answer 4

How much energy is needed by a charge to push the current through the circuit.

Question 5

Equation for charge

Answer 5

charge(coulombs/ c) = current x time(s)
(Q = I x T)

Question 6

Equation of potential difference

Answer 6

Potential difference = current x resistance
(V = I x R)

Question 7

What is resistance measured in?

Answer 7

Ohms

Question 8

What is the relationship between the length of the wire and the resistance of the circuit?

Answer 8

It is directly proportional. When the length increases, the resistance increases too. The longer a piece of wire is, the more difficult it is for the current to flow. The graph is a straight line through the origin.

Question 9

What are electrical insulators?

Answer 9

Meterials with extremely high resistance

Question 10

What is the relationship between current and potential difference for a fixed resistor?

Answer 10

A straight line through the orgin, directly proportional. As the current increases, the potential difference increases. The resistance remains constant as the current changes. It means that it is an ohmic conductor.

Question 11

What is the relationship between the current and potential difference for a lamp?

Answer 11

The graph is a curve. The resistance of the bulb increases as the current and the potential difference increases. This is because the bulb gets hotter as more current flows through it and the temperature of it increases.

Question 12

What is the relationship between resistance and temperature for a thermistor?

Answer 12

resistance decreases as temperature increases, used in thermometers, thermostats, electric kettles etc.

Question 13

What is the relationship between resistance and light intensity for a LDR?

Answer 13

resistance of LDR decreases when light intensity increases, used in light sensors and street lamps

Question 14

Rules of current, p.d. and resistance for series circuits

Answer 14

• Current: current is the same everywhere
• P.d: p.d. of power supply is shared between the components
• Resistance: the total resistance of the circuit is the sum of all of the individual resistances

Question 15

Rules of current, p.d., and resistance in parallel circuits

Answer 15

• Current: splits when it reaches a junction
• P.d. is the same in each branch
• Resistance: the more routes you provide for the current to flow, the easier it is for the current to flow though

Question 16

What is the relationship between the current and potential difference for a diode?

Answer 16

• graph is a curve
• resistance decreases as the current and p.d. increase
• no current can flow when it is turned around as the resistance is too high

Question 17

What is static electricty?

Answer 17

• charge that builds up because it is not able to flow away into the surroundings
• electrons become static in movement

Question 18

How can objects be charged?

Answer 18

• when electrons are transferred to or from an object

Question 19

what happens when the material gains electrons?

Answer 19

• becomes negatively charged

Question 20

What happens when the material loses electrons?

Answer 20

• gains a positive charge

Question 21

What causes sparks?

Answer 21

• when electrons discharge to a conducting material or to the ground through the air
• the object becomes discharged or earthed

Question 22

How are electric fields drawn?

Answer 22

• from positive to negative
• stronger field= more field lines
• spread from single point