Topic 3

Question 1

What is the definition for current

Answer 1

Rate of flow of charged particles

Question 2

What are the equations for voltage

Answer 2

V=IR

V=W/Q same as V=E/Q

Question 3

What is ohms law

Answer 3

When voltage is proportional to current the resistance can be sound by the gradient if the temperature is constant

Question 4

What is Kirchhoffs law

Answer 4

Sum of current at a junction is equal to 0

Question 5

How is charge conserved

Answer 5

No clue mate, current stays same in series?

Question 6

How is potential difference distribution energy concentration

Answer 6

Total voltage of all the components in the circuit equal the voltage supplied

Question 7

How does voltage, current and resistance act in series

Answer 7

Vtotal=V+V+V
Itotal=same everywhere
Rtotal=R+R+R

Question 8

How does voltage, current and resistance act in parallel

Answer 8

1/Vtotal=Same on each branch
Itotal=I+I+I
1/Rtotal=1/R+1/R+1/R

Question 9

What is the relationship between V and I in a filament bulb

Answer 9

Small V = proportional to I

Large V = not proportional to I

Question 10

What does a diode do to the current

Answer 10

Only allows it to flow in one direction, and at a threshold voltage in the correct direction

Question 11

How does voltage vary with the length of the wire

Answer 11

Due to R increasing with length of a wire, this means that voltage will also increase

V=AΔx

Question 12

What are semiconductors?

Answer 12

A material with only a small number of delocalised electrons

Question 13

How do semiconductors work?

Answer 13

Have different conduction bands, valance band is when electrons are stuck to the atoms, conduction band is when they are delocalised and can carry a charge.
Insulators have an empty conduction band and full valence band
Semiconductors have an almost empty conduction band and almost full valence band
Metals have an almost empty valence band and an almost full conduction band

Question 14

What is superconductivity

Answer 14

Reducing the temperature reduces the resistance because particles do not vibrate as much, bellow a critical temperature resistance is 0 is -243*C for most metals

Question 15

What are the characteristics of a semiconductor diode

Answer 15

Has a energy barrier junction that blocks movement of charge carriers, only a small amount leaks through, once voltage is high enough it can break through the barrier.

Question 16

How do LDRs work?

Answer 16

Made from semiconductor material, more light boosts electrons to the conduction band.

Question 17

What is the electric current rule

Answer 17

Sum of current entering a junction =0

Question 18

What is the voltage rule

Answer 18

Total V is equal to all p.d across components added together

Question 19

What is the purpose of a potential divider?

Answer 19

To change the amount of voltage given to a component by changing the resistance

Question 20

What is the potential divider equation?

Answer 20

Vout = Vin * R2/R1+R2

Question 21

What is emf

Answer 21

Electromotive force is how much chemical energy is being supplied to provide a an electrical potential difference

Question 22

What is emf

Answer 22

Electromotive force is the amount of energy in volts that is being supplied to provide a an electrical potential difference in a circuit

Question 23

What is internal resistance

Answer 23

The resistance of an emf source

Question 24

What is the internal resistance equation

Answer 24

ε = V + Ir