Unit 2: Electricity (Circuits)

Question 1

Current

Answer 1

The rate of flow of electric charge

Question 2

Unit for current

Answer 2

Amperes/Amps

Question 3

Voltage

Answer 3

The energy transferred per coulomb of charge

Question 4

Unit for voltage

Answer 4

Volts (V); the transfer of 1 joule of energy by 1 coulomb of charge

Question 5

Equation energy transferred

Answer 5

E (energy transferred) = Q (charge) x V (voltage)

Question 6

Equation electric charge

Answer 6

Q (charge) = I (current) x t (time)

Question 7

Resistance

Answer 7

The oppsition to the flow of electric current (units: ohms); the higher the resistance, the lower the current

Question 8

Resistance equation

Answer 8

V (voltage) = I (current) x R (resistance)

Question 9

Current in series

Answer 9

All components have same current. Current increases if voltage of power supply increases. It decreases if number of components increase

Question 10

Current in parallel

Answer 10

Different values at different points; splits at junctions, not always equally

Question 11

Where does current flow?

Answer 11

Positive to negative terminal

Question 12

Voltage in series

Answer 12

Shared between components; not always equally between non- identical components with different values of resistance

Question 13

Voltage in parallel

Answer 13

Total voltage across each branch is the same as the voltage of the power supply

Question 14

Advantages series

Answer 14

All components controlled by single switch, fewer wires required

Question 15

Disadvantages series

Answer 15

Comp. cannot be controlled separately, if one component breaks all other components stop working

Question 16

Advantages parallel

Answer 16

Comp. can be individually controlled using own switches, if one comp. breaks others will continue to function

Question 17

Disadvantages parallel

Answer 17

• More wires involved
• All branches have same voltage as supply which makes it difficult to control voltage across individual components

Question 18

Total voltage, total resistance (series)

Answer 18

Sum of voltages across each of the individual resistors, sum of individual resistances

Question 19

Series summary

Answer 19

• Current is same at each point & in each component
• Voltage of power supply shared between components
• Total resistance is sum of resistances of each component

Question 20

Parallel summary

Answer 20

• Current splits in branches
• Voltage across each branch is same
• Total resistance is less than that of each component

Question 21

Thermistor

Answer 21

Resitance depends on temperature; high resitance in cold, low resistance in hot

Question 22

Light- dependent resistor

Answer 22

Resistance depends on light intensity; high resiatnce in dark, low resistance in bright