Electricity

Question 1

What is electric current is defined as

Answer 1

The rate of flow of charge

Question 2

What is the equation for current

Answer 2

Current= charge possible point/time taken

I (amps) = Q (coulomb (C))/T (must be in seconds)

Question 3

What does voltage measure

Answer 3

Voltage (or potential difference) measures the energy given to components when charges go through them

Question 4

What is the equation for voltage

Answer 4

Voltage= Energy transfer/charge

V = E (Joules (J))/ Q(coulombs( C))

Question 5

What happens when you put two bulbs in a series circuit

Answer 5

The Amsterdam because the resistance is greater. The brightness also goes down

Question 6

-------|||-------
|                     |
A1                  |
|                     |
---A2--bulb---
|                     |
A3.                |
|                     |
-----bulb-----
What is the relationship between A1, A2 and A3
What happens to the current at the junction

Answer 6

A1=A2+ A3

It is being split (doesn’t have to be even)

Question 7

What are coulombs

Answer 7

Electrons have a small amount of charge it is measured in coulombs

Question 8

What is current

Answer 8

The rate of flow of charge

Current= charge/time
I= Q/T

Question 9

What is an amp equal to

Answer 9

1amp = 1 C per second

Question 10

How is an ammeter placed in a circuit

Answer 10

It is always placed in series with the device

Question 11

How does an ammeter work

Answer 11

The ammeter records how long it takes for the coulomb to flow through it and then uses the equation: current = charge/time

Question 12

What is 1 V equal to

Answer 12

One joule per coulomb. This means that one coulomb would have done one joule of electrical energy. The greater the voltage, the greater the amount of energy 1 C of charge has

Question 13

What will varying the resistance of a variable resistor do

Answer 13

It will vary the potential difference (voltage) across the resistor

Question 14

What is the equation that links current, voltage and resistance together

Answer 14

Voltage= current x resistance

Question 15

What does Ohms law state

Answer 15

It states that voltage and current are directly proportional, provided that other physical properties (like temperature) remain constant.
This means that an I-V graph would be a straight line that the passes through the origin

Question 16

Does a filament lamp obey Ohms law. explain your answer

Answer 16

No. Because the graph is the curve, not a straight line
This is because there is more resistance because the higher temperature of the brighter lamp gives the ions more energy. This is shown because the gradient is getting less

Question 17

How does resistance vary with light intensity in a light variable resistor

Answer 17

As it gets dimmer, the higher the resistance. It is inversely proportional

Question 18

How does resistance very with temperature and a thermistor

Answer 18

As the temperature increases, the resistance of a thermistor decreases
Resistance and temperature are inversely proportional

Question 19

Define electric current

Answer 19

Flow of charges. This is the flow of charge is around the circuit, usually the charge of electrons

• In metal the current is due to electrons flowing from the negative side to the positive side
• Electrolysis, the current consist of positive ions moving to the cathode and negative ions to the anode

Question 20

Filament lamp

Answer 20

An s shape but without the bit on the end that dips down

Goes through the origin

Question 21

LDR GRAPH

Answer 21

Current increases as resistant decreases

Through the origin rising to top right

Question 22

Thermistor graph

Answer 22

Y=1/x
Slopes down from top left to bottom right
Not straight line, curves

Question 23

Diode graph

Answer 23

Just under 0 in the -ve bit of graph

At 0it raises just above, at 0.7 it sharply increases