Tag: household circuits

Quizzes (4) Questions (39)

Questions Related to household circuits

Multiple choice power transmission household electricity household circuits electricity and magnetism physics

Transmission lines transmit a voltage of $V$ volt to our houses from power stations, then the power $P$ supplied by them is proportional to:

  1. $\cfrac{1}{V}$
  2. $V$
  3. ${V}^{2}$
  4. $\cfrac{1}{{V}^{2}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Power supplied is equal to to the voltage multiplied by the current flowing through the wire.

  $\therefore$     $P = VI$
$\implies  P  \propto  V$

Multiple choice power transmission household electricity household circuits electricity and magnetism physics

From a power station, the power is transmitted at a very high voltage because :

  1. It is generated only at high voltage

  2. It is cheaper to produce electricity at high voltage

  3. Electricity at high volatge is less dangerous

  4. There is less loss of energy in transmission at high voltage
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When power is transmitted from power station to different different substation then one important factor is kept in mind that power loss in pathway during transmission over large distances should be minimum. 

we know that P = V I 
so for a particular power that is to be transmitted we can choose a combination of voltage and current so that loss is minimum as much possible.
if we do current high and voltage minimum then due to high current , heat loss will be more and power will get lost , hence voltage is kept high and current is kept low as much possible so that current can not produce high vibrations and collisions  in free electrons insides the wire making a lot of loss of power.
so by keeping voltage to high value the loss is minimum as compared to other cases.

Multiple choice power transmission household electricity household circuits electricity and magnetism physics

The heart does $1.5\ J$ of work in each heart beat. How many times per minute does it beat if its power is $2W$?

  1. $20$
  2. $40$
  3. $60$
  4. $80$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Power is defined as work done per unit time, or P = W_total / t. Total work per minute is number of beats (n) multiplied by work per beat (1.5 J). Thus, 2 W = (n * 1.5 J) / 60 s, which yields n = (2 * 60) / 1.5 = 80 beats per minute.

Multiple choice power transmission household electricity household circuits electricity and magnetism physics

A boy of mass $55\ kg$, runs up a flight of $40$ stairs, its measuring $0.15\ m$ in $15\ s$, the power developed by the boy in kilowatts and Horse power is

  1. $220$ and $0.29$
  2. $625$ and $0.83$
  3. $1.15$ and $0.83$
  4. $6.25$ and $0.83$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Work = m * g * h = 55 * 9.8 * (40 * 0.15) = 55 * 9.8 * 6 = 3234 Joules. Power = Work / Time = 3234 / 15 = 215.6 Watts = 0.2156 kW. 1 HP = 746 Watts, so 215.6 / 746 = 0.289 HP. Option A is the closest.

Multiple choice physics household circuits precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

Wires used for electric supply go are generally made up of:

  1. silver

  2. aluminium

  3. copper

  4. both b and c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electric is generated at power station. It is brought to one house by two thick copper wires or aluminium wires fixed once fall electric poles

Multiple choice physics household circuits precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

High tension wires has

  1. high resistance.

  2. low resistance.

  3. high young's modulus.

  4. low young's modulus.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

High tension wire is made by twisting together a number of thin wires insulated from each other so as to provide large surface area. It helps to radiate more heat and prevents burning of wire.

Multiple choice physics household circuits precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

A high tension wire has a _____ resistance. Fill in the blank.

  1. Low

  2. High

  3. Equal

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A high tension wire has a low resistance and large surface area. Instead of taking a single thick wire of low resistance, it is made by twisted together a number of thin wires insulated from each other so as tat it can radiate the head provided.

Multiple choice physics household circuits precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

A bulb of 40W is producing a light of wavelength 620 nm with 80% of eficiency then no of photons emitted by the bulb in 20 sec are 

  1. $2 \times (10) ^ {18}$
  2. $10 \times (10) ^ {18}$
  3. $10 \times (10) ^ {21}$
  4. $2 \times (10) ^ {20}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Energy of photon emitted by a bulb,

$E=\dfrac{80}{100}\times 40\times 20=640$
Wavelength of light, $\lambda=620nm$
Energy of photons $E'=\dfrac{hc}{\lambda}$
$=3.2\times 10^{-19}J$
$\therefore$ No of photons emitted , $n=\dfrac E{E'}$
$=\dfrac{640}{32\times 10^{-19}}$
$=2\times 10^{20}$