Tag: electric power

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Questions Related to electric power

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

Each electrical appliance is provided with a _______ core flexible cable. Fill in the blank.

  1. 3

  2. 2

  3. 1

  4. 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Each electrical appliance is provided with three (3) core flexible cables. The insulation on the three wires is of different colours i.e  Brown for live wire, blue for neutral wire and green or yellow for earth wire.

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

For a domestic $AC$ supply of $220\ V$ at $50$ cycles per second the potential difference between the terminals of a two-pin electric outlet in a room is given by

  1. $V(t) = 220\sqrt {2}\cos (100\pi t)$
  2. $V(t) = 220\cos (50t)$
  3. $V(t) = 220\cos (100\pi t)$
  4. $V(t) = 220\sqrt {2}\cos (50 t)$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rms value of voltage  $V _{rms} =220 $ volts

Peak value of voltage  $V _o = \sqrt{2}V _{rms}$
$\therefore$ $V _{o} = 220\sqrt{2}$volts   
Frequency  $\nu =50$ $Hz$
$\implies$  $w = 2\pi \nu = 2\pi (50)  = 100\pi$
Thus potential difference is given by  $V = V _o \cos wt$
$\therefore$  $V= 220\sqrt{2} \cos (100 \pi t)$

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

Which instrument is not used to convert electric energy into heat energy?

  1. Room heater

  2. Electric Iron

  3. Electric Bell

  4. Electric water heater
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electric Bell is not used to convert electric energy into heat energy as there is no  use of heat in functioning of an electric bell.In electric bell electrical energy is used to convert sound energy.First it converts electric energy into mechanical energy and which is used to produce sound energy.

Therefore,C is correct option.

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

Household electrical appliances are joined using ________ combination of resistors

  1. Parallel

  2. Alternating

  3. Continuous

  4. Series
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a house, there are many electrical appliances that have to run independent of each other. If one appliance is turned on or off it should not affect the other appliances. Thus even if a single appliance is taken out of the circuit (turned off / open switched ) the circuit breaks and hence the current cannot flow in the circuit so every thing turns off.

 So even if a single appliance is taken out of the circuit (turned off / open switched ) the circuit breaks and hence the current cannot flow in the circuit .
In parallel, even if an appliance gets damaged or is turned off ,the current always has other independent dedicated parallel paths to other appliances and hence every appliance is still works well.