P4 - Electrical Circuits

Question 1

What is a battery?

Answer 1

2 or more cells joined together.

Question 2

Ohm’s law?

Answer 2

Current through a resistor at a constant temp is directly proportional to the potential difference across the resistor.

Question 3

Reversing the potential difference through a resistor….

Answer 3

Reversed the current through it.

Question 4

Why do insulating materials become charged?

Answer 4

because electrons are transferred

Question 5

D. Current

Answer 5

Flow of charge

Question 6

What is electric charge measured in?

Answer 6

coulombs

Question 7

D. Diode?

Answer 7

a non-ohmic conductor that has a much higher resistance in one direction then the other so allows current only one way.

Question 8

1 Amp is….

Answer 8

I coulomb/second

Question 9

Why are voltmeters connected in parallel?

Answer 9

So that it measures the voltage across something/a component

Question 10

Current is directly proportional to….

Answer 10

resistance

Question 11

D. Thermistor

Answer 11

A temperature-dependant resistor, temp increase = resistance decrease

Question 12

E. Total resistance for a series circuit

Answer 12

T.R = R1+R2+R3 etc

Question 13

E. Total resistance for a parallel circuit?

Answer 13

1/t.r = 1/R1 + 1/R2

Question 14

In a series circuit?…. (current and P.D)

Answer 14

Current is the same everywhere, P.D is shared equally through the components

Question 15

In a parallel circuit….

Answer 15

Current is split and P.D is the same everywhere?

Question 16

Putting more resistors in parallel….

Answer 16

Decreases total resistance of circuit because total current through them is increased and P.D is unchanged

Question 17

Why does a filament lamp’s resistance change as P.D changes?

Answer 17

Because as P.D increases the temp increases, so the metal ions have more k.energy and vibrate more vigorously and so it is harder for the electrons to pass through them, which means that the resistance is increased.