Tag: effects of electric current

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Multiple choice physics effects of electric current thermal effect of electric current heating effect of electric current electric current and its effects

Calculate the monthly bill if a heater of 100 watt is used at the rate of rs. 1 per unit for 1 hour daily.

  1. Rs. 200

  2. Rs. 6000

  3. Rs. 100

  4. Rs. 3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given :       $P=0.1$ kW           $t = 1$ hour per day

Energy consumed per day     $E = Pt = 0.1\times 1 = 0.1$ kWh per day
Total energy consumed per month  $E _T = 30\times 0.1 = 3$ kWh per month
Cost of electricity  $ =Re$ $ 1 $ per unit i.e per kWh
$\therefore$  Monthly bill $ = Re.$ $1\times 3   =$Rs. $3$ per month

Multiple choice physics effects of electric current thermal effect of electric current heating effect of electric current electric current and its effects

Calculate the total power of 2 fans, if each of them draws a current of $5   A$ at a p.d of $200   V$.

  1. $2000 \omega$
  2. $1000 V$
  3. $250 \omega$
  4. $2 \omega$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$I = 5A,   p.d = 200   V$
Power $= V \times I = 200 \times 5 = 1000   \omega$
For 2 fans $= 2 \times 1000 = 2000   \omega$.

Multiple choice physics effects of electric current thermal effect of electric current heating effect of electric current electric current and its effects

Calculate the energy transferred by a $5  A$ current flowing through a resistor of $20   \ ohms$ for $30$ minutes.

  1. $25 kwh$
  2. $50 kwh$
  3. $2.5 \times {10}^{-2} kwh$
  4. $5 \times {10}^{-2} kwh$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$E = {I}^{2}Rt$
$= {5}^{2} \times 2 \times \dfrac{1}{2}$
$= 2.5 \times {10}^{-2}  kwh$

Multiple choice physics effects of electric current thermal effect of electric current heating effect of electric current electric current and its effects

A bulb of $2.5  V$, draws a current of $0.5  A$. If the bulb is switched on for 2 minutes, calculate the energy released by the bulb.

  1. $1.25 J$
  2. $260 J$
  3. $5 J$
  4. $150 J$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

P.D $= 2.5   V$
Current $= 0.5   A$
$t = 2$ minute $= 2 \times 60 = 120  s$
$ E = V \times I \times t = 2.5 \times 0.5 \times 120 = 150   J$.

Multiple choice physics effects of electric current thermal effect of electric current heating effect of electric current electric current and its effects

A light bulb has the resistance of tungsten resistance which convert about 10% electrical energy into visible light.  If energy other than visible is waste energy. How many kilo-joules does a light bulb wasted in one hour?

  1. 36 kJ

  2. 90 kJ

  3. 3240 kJ

  4. 360 kJ

  5. 32,400 kJ
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
$90$ % of electrical energy is wasted in one hour.
Using        $1kWh  = 3600$ $kJ$
$\therefore$ Energy wasted       $E _{waste} = 0.9 \times 3600  =3240$  $kJ$