Tag: effects of electric current

Questions Related to effects of electric current

Joule's effect is due to:

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. Collision of electrons

  2. Collision of free electrons with positive ions

  3. Collision of positive ions

  4. All

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Correct Option: B
Explanation:

Joule's effect is due to collision of free electrons with positive ions.

A/c to Joules's law, if the potential difference across a conductor having a material of specific resistance (P) remains constant, then the heat produced in the conductor is directly proportional to

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. $\displaystyle P$

  2. $\displaystyle { P }^{ 2 }$

  3. $\displaystyle \frac { 1 }{ \sqrt { P } } $

  4. $\displaystyle \frac { 1 }{ P } $

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Correct Option: D
Explanation:

Let the specific resistance of the material be  $P$.

$\therefore$  Resistance of the conductor        $R = \dfrac{P L}{A}$
According to Joule's heating effect,  heat produced     $H = \dfrac{V^2t}{R}$

$\therefore$   $H = \dfrac{V^2 t}{PL/A}  = \dfrac{V^2A t}{L}\dfrac{1}{P}$              $\implies H\propto \dfrac{1}{P}$

Joule's heating effect is

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. Reversible

  2. Irreversible

  3. Both

  4. None

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Correct Option: B
Explanation:

Joule heating effect is irreversible that means if the direction of current in a resistor is reversed, the cooling of resistor does not occur whereas heating of the resistor takes place.

Heat produced via Joule's heating effect    $H = i^2Rt$ 

From Joule's Law of heating, the heat produced, $H =$

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. $\dfrac{{I}^{2}}{Rt}$

  2. $\dfrac{{I}^{2}R}{t}$

  3. $\dfrac{{R}^{2}I}{t}$

  4. ${I}^{2}Rt$

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Correct Option: D
Explanation:

Work done (heat produced) $= {I}^{2}Rt  \   Joule$


$I=$ current, $R =$ Resistance

$t =$ time in seconds

J (Joule's mechanical equivalent of heat) is equal to

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. 2400J

  2. $\displaystyle 4.18J{ cal }^{ -1 }$

  3. $\displaystyle 2.2J{ cal }^{ -1 }$

  4. 1000J

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Correct Option: B
Explanation:
According to Joule's law, mechanical equivalent of heat    $J = \dfrac{W}{Q}$
Mathematically    $J = 4.18$  $Jcal^{-1}$ if work done and heat produced is measured in joules and calories respectively.

From below which one is the equation for Joule's law of heating effect of electricity?

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. $H=I^2Rt$

  2. $H=IR^2t$

  3. $H=IRt^2$

  4. $H=\dfrac{It^2}{R}$

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Correct Option: A
Explanation:

According to Joule's law of heating,  heat produced in a resistor     $H = I^2Rt$

where $I$ and $t$ are the current flowing through the resistor and time of current flowing respectively.

If a current $i$ flows steadily through a resistor $R$ for a time $t$. Then total heat energy supplied to the resistor is given by:

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. $\dfrac{R}{it}$

  2. $iR^{2}t^{2}$

  3. $i^{2}Rt$

  4. $V^{2}it$

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Correct Option: C
Explanation:

According to Joule's law of heating, total heat energy supplied to the resistor, $H=i^{2}Rt$

 When electric current is passed through conductor i.e. generates heat due to resistance it offers to current flow. What this phenomena known as :

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. Burning effect of electricity

  2. Potential Effect of electricity

  3. Heating effect of electricity

  4. Floating effect of electricity

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Correct Option: C
Explanation:

The phenomenon of generating heat due to the resistance of the conductor when a current passes through it is known as heating effect of electricity.

Heat produced     $H = I^2Rt$

Which of the following terms does not represent electrical power in a circuit?

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. $I^2R$

  2. $IR^2$

  3. $VI$

  4. $V^2/R$

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Correct Option: B
Explanation:

$P=VI\quad .............(i)$

Hence, option (c) represents power.
$V=IR\quad .............(ii)$

From (i) and (ii),
$P=I^2R$
$P=V^2/R$
Hence, option (a) and (d )represents power too.
Option (b) does not represent power.

A $1000\Omega$ electric iron is connected to $200v$, $50Hz$ ac source. Calculate average power delivered to iron, peak power and energy spent in one minute?

physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

  1. $400W,\ 800W,\ 12\times 10^{5}\ J$

  2. $400W,\ 900W,\ 1.2\times 10^{5}\ J$

  3. $500W,\ 800W,\ 6\times 10^{5}\ J$

  4. $400W,\ 900W,\ 60\times 10^{5}\ J$

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Correct Option: A