Current Electricity (ii)

Question 0

Voltage

Answer 0

The amount of energy per Coulomb. 1 volt equals 1 Joule per Coulomb.

Question 1

Current

Answer 1

The rate of flow of charge. 1 amp is equal to 1 coulomb per second. The charge carriers are delocalised electrons in wires.

Question 2

Voltmeters measure

Answer 2

Energy in a circuit

Question 3

Potential difference is

Answer 3

Voltage

Question 4

Ohms law

Answer 4

Current is directly proportional to voltage, provided that other physical properties (like temperature) remain constant

Question 5

Ohms law equation

Answer 5

Voltage = current x resistance
Volts (V) = Amps (A) x ohms (ohms sign)
V = I x R

Question 6

Describe how current varies with voltage

Answer 6

As voltage increases so does the current

Question 7

I-V graphs for a resistor

Answer 7

• resistance = 1/gradient
• current and resistance are inversely proportional
• resistance restricts the flow of current
• low R = high I
• high R = low I

Question 8

Learn the symbols of a circuit

Answer 8

Workbook

Question 9

Diodes allow

Answer 9

Current to flow in one direction

Question 10

Diodes facing the direction of the current is called

Answer 10

Forward bias (current always flows from +ve to -ve)

Question 11

Diode facing the opposite of direction of current flow is called

Answer 11

Reverse bias and current will not flow

Question 12

LED

Answer 12

Light emitting diode that will light up when current flows through it at forward bias as long as the voltage is above 0.6V. It will not light up when current flows through it at reverse bias .

Question 13

LDR

Answer 13

Light dependent resistor

As light intensity increases resistance decreases

Question 14

Thermistor

Answer 14

As temperature increase resistance decreases

Question 15

How does current vary with voltage in forward bias

Answer 15

Current increases more rapidly than voltage

Question 16

Describe how current varies with voltage in reverse bias

Answer 16

The more the voltage increase, the current still remains at 0. If more voltage is used, the current would still be at 0 but would eventually break

Question 17

What is a diodes purpose

Answer 17

Allows current to flow in one direction

Question 18

How does the length of a wire effect its resistance

Answer 18

• The longer the wire the higher the resistance (directly proportional)
• sources of error: crocodile clips resisted themselves, the wire was not completely flat therefore the length of the readings would be smaller and imprecise, dont know where to take the readings from as the clips are so thick so dont know where electrical contact is made

Question 19

Name an advantage and disadvantage of a parallel circuit compared to a series circuit

Answer 19

Adv: individual control of each appliance, if one appliance breaks the rest dont
Disadv: if little appliances need to all work at the same time in parallel, the power supply would overheat and become a fire hazard

Question 20

Energy transferred=

Answer 20

Current x voltage x time

Question 21

Rule for current in a series circuit

Answer 21

Current remains constant throughout a series circuit

Question 22

Rule for voltage in a series circuit

Answer 22

Voltage of the cell is equal to the sum of potential differences

Question 23

Rule for current in parallel circuit

Answer 23

Current splits at a junction, however comes out as the same value even if it was split unevenly

Question 24

Rule for voltage in parallel circuit

Answer 24

The same amount of energy/voltage is ‘used’ per circuit of the parallel circuit

Question 25

Current equation

Answer 25

I = Q/t
Current = charge/ time
A = C/t

Question 26

Voltage equation

Answer 26

V= E/Q
Voltage = energy / charge
V = J/C

Question 27

Resistance

Answer 27

Ratio of voltage: current or restricts the flow of current

Question 28

Merge the equations Q=It and E=VQ

Answer 28

E = ItV
Energy = current x time x voltage
J = A x s x V

Question 29

I-V for a diode

Answer 29

• at one point in the graph resistance starts to decrease in order to let the current flow
• reverse bias however, the resistance remains massive and never decreases therefore preventing a large current flow

Question 31

Answer some circuit questions

Answer 31

In workbook