Tag: heating effect of electric current- uses

Questions Related to heating effect of electric current- uses

From below which are the applications of heating effect of electric current?

  1. Electric immersion water heater

  2. Electric Iron Box

  3. Electric Fuse

  4. All of the above


Correct Option: D
Explanation:

According to heating effect of electric current, heat is produced in the materials that have resistance, thus electric immersion water heater, electric iron box and electric fuse are the applications of heating effect of electric current.

Why are bulbs filled with chemically inactive Nitrogen or Argon gas?

  1. To prevent oxidation of Tungsten filament

  2. To prevent dehydration of Tungsten filament

  3. To prevent oxidation of Steel filament

  4. None


Correct Option: A
Explanation:

Bulbs are filled with chemically inactive Nitrogen or Argon gas to prevent the oxidation of tungsten filament used in the bulb.

An electric fuse used in households works on which principle of:

  1. Joule's heating

  2. Coulomb's law

  3. Maxwell's law

  4. Ohm's law


Correct Option: A
Explanation:

An electric fuse in households works on the principle of Joule's heating that heat produced due to the excess current flowing through it melts the fuse wire which cut off the circuit and hence the appliance is prevented from damage.

Why is electric power transmitted over long distances at high voltage?

  1. To minimize power loses due to Joule's heating

  2. To maximize power loses due to Joule's heating

  3. To balance power loses due to Joule's heating

  4. None


Correct Option: A
Explanation:

For constant electric power, higher the voltage, lower is the current (as $P=IV$) through the wire. As power loss due to Joule's heating is proportional to $I^2$, for a small current, power loss is also small. So, power is transmitted over long distances at high voltage to minimize power loses due to Joule's heating.

A vertical wire caries a current in upward direction. An electron beam sent horizontally towards the wire will be deflected

  1. towards right

  2. towards left

  3. upwards

  4. downwards


Correct Option: C
Explanation:

Using Right-Hand thumb rule and (Flemmings Left Hand Rule, current direction (i) = Left Side Magnetic field  (B) = outwards, so the direction of the force is upwards.

When a metallic conductor is heated then the atoms in the metal vibrate with ?

  1. low amplitude and frequency.

  2. greater amplitude and frequency.

  3. greater amplitude and low frequency.

  4. less amplitude and greater frequency.


Correct Option: B
Explanation:

When a metallic conductor is heated its atoms get more energy and get agitated. That is why they vibrate with greater amplitude and frequency.

Thermal energy produced by the resistance R in time duration 1 $ \mu s $. using the source at resonance condition is 

  1. 0 J

  2. $ 1 \mu J $

  3. $ 100 \mu J $

  4. not possible to calculate from the given information.


Correct Option: D

Current through resistor of resistance $R$ varies with time as $I = I _ot$. What will be the time taken to deliver heat $H$ by this resistor?

  1. $\left( \cfrac { H } { I _ { 0 } R } \right) ^ { 1 / 2 }$

  2. $\left( \cfrac { H } { 3 I _ { 0 } ^ { 2 } R } \right) ^ { 1 / 3 }$

  3. $\left( \cfrac { 3 H } {I _ { 0 } ^ { 2 } R } \right) ^ { 1 / 3 }$

  4. $\left( \cfrac { H } { I _ { 0 } ^ { 2 } R } \right) ^ { 1 / 3 }$


Correct Option: C

If p.d. across a conductor is constant and resistivity of its material is $\rho $, the joule heat produced in 1 s is proportional to .. 

  1. $\dfrac{1}{\rho }$

  2. $\dfrac{1}{{\sqrt \rho }}$

  3. $\rho $

  4. ${{\rho ^2}}$


Correct Option: A

A coal based thermal power plant producing electricity operates between the temperatures $27^o C$ and $227^o C$ The plant works at 80% of its maximum theoretical efficiency. Complete burring of 1 kg of coal yields 3600 KJ of heat. A house needs 10 units of electricity each day. Coal used for supplying the amount of energy for the house in one year is 

  1. 1141 kg

  2. 580 kg

  3. 605 kg

  4. 765 kg


Correct Option: B