Electricity

Question 1

Rule of thermistors

Answer 1

T emperature
U p
R esistance
D own

Question 2

Rule of light dependant resistors

Answer 2

L ight
U p
R resistance
D own

Question 3

Electrical current

Answer 3

Electric current is the rate of flow of charge (Q) (coulombs)

Question 4

ACDC

Answer 4

Alternating current - produces a flow that reverses in direction many times per second

direct current - produces a flow of charge in one direction

Question 5

Relationship:

Voltage in series

Answer 5

Divides

VT= V1 + V2 + V3

Question 6

Relationship:

Current in series

Answer 6

Current in series is equal

IT = I1+ I2 + I3

Question 7

Resistance in series

Answer 7

Divides

RT = r1+r2+r3

Question 8

Voltage parallel

Answer 8

Equal

Vt= v1 = v2 = v3

Question 9

Current in parallel

Answer 9

Divides

It= I1+ i2 + i3

Question 10

Resistance in parallel

Answer 10

Decreases as no. Of branches increase

1/Rt = 1/R1 + 1/r2 + 1/r3

Question 11

Transistor

Answer 11

A voltage controlled switch

Question 12

Different kinds of transistors

Answer 12

NPN - 0.7v or greater (switch on at)

MOSFET - 2v or greater

Question 13

Electric field

Answer 13

Region of space where force is felt

Question 14

What are electric fields caused by

Answer 14

Charges repelling and attracting
Like charges repel - electron to electron
Opposite charges attract - electron to proton

Question 15

Voltage

Answer 15

Joules per coulomb of charge

Question 16

Where does voltage come from?

Where do we find this?

Answer 16

The electric field supplies energy to the charges

Electric field provided by the power supply

Question 17

How do you calculate the voltage across resistors in a voltage divider circuit?

Answer 17

1. Apply ohms law
   - once to whole circuit for current
   -then to individual resistor
   Or
2. Use Eq.
   V1/vt = r1/rt

Question 18

Power

Answer 18

Power is the energy used per second

Question 19

What can’t led’s do??

To solve?

Answer 19

Can’t allow too much current to pass through
Place in series with a resistor
To make sure current flows - place arrows downwards negative part of supply as it only allows current to flow in one direction

Question 20

When temperature of conductor is increased?

Answer 20

Resistance increases

Current decreases

Question 21

Ammeter must be connected in

Answer 21

Series

Question 22

Voltmeter connected in

Answer 22

Parallel

Question 23

Resistance

Answer 23

Measure of how much a component or circuit opposed the flow of current

Question 24

Bigger the resistance

Answer 24

Smaller current

Question 25

Voltage increases

Answer 25

Current increases in direct proportion