3.1 Current and Potential Difference

• A

• B

• C

• D

Which pattern of the distribution for castor powder is formed when the switch is turned on ?

• 
• 
• 
• 

• Remains at plate X

• Move towards centre and remains at centre

• Move towards Y and remains at Y

• Move continuously between X and Y

• Plate X - positive

  Plate Y - negative

• Plate X - positive

  Plate Y - positive

• Plate X - negative

  Plate Y - positive

• Plate X - negative

  Plate Y - negative

When a test charge of 0.25 μC is placed in an electric field, it experiences a force of 0.18 N acting on it. Calculate the strength of the electric field experienced by the electric charge ?

• 0.72 NC^-1

• 0.72 x 10⁵ NC^-1

• 7.2 x 10⁵ NC^-1

• 7.2 x 10^-5 NC^-1

The charge flowing in an electric circuit in one minute is 6.0 C. What is the current in this circuit ?

• 0.1 A

• 1.0 A

• 10.0 A

• 100.0 A

An electric current of 300 mA flows through a resistor in 6 seconds. How many electrons pass through the resistor ?

(Charge per electron = 1.60 x 10 ^-19 C)

• 3.750 x 10¹⁸

• 1.125 x 10¹⁹

• 3.750 x 10²¹

• 1.125 x 10²²

An electric kettle labelled 220 V, 1000 W is used to boil water for 10 minutes. If the flowing current is 4.5 A, calculate the amount of charges that flow in the kettle.

• 225 C

• 675 C

• 1350 C

• 2700 C

Lightning is an example of electric current. In a typical lightning, the flash takes 0.2 s to transfer 10⁹ J of energy across a voltage of 5 x 10⁷ V. Use the information given, calculate the amount of charge transferred and the current flows in 0.2 s.

• Q = 10 C , I = 100 A

• Q = 20 C , I = 200 A

• Q = 20 C , I = 100 A

• Q = 10 C , I = 100 A

An electric kettle is used to boil water, it is found that the current that flows through the heating filament of the kettle is 5 A and the total charge that flows through the filament is 3000 C. What is the time taken to boil the water ?

• 10 s

• 15000 s

• 600 s

• 500 s