Tag: physics

Questions Related to physics

The power factor of a circuit in which a box having unknown electrical devices connected in series with a resistor of resistance $3\Omega$ is $3/5$. The reactance of the box is

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. $5\Omega$

  2. $\dfrac{5}{3}\Omega$

  3. $4\Omega$

  4. $\dfrac{4}{3}\Omega$

Show answer
Correct Option: B

The tolerance for silver color in color coding of a resistor is:

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. $10$%

  2. $5$%

  3. $1$%

  4. $15$%

Show answer
Correct Option: A
Explanation:

The tolerance of silver colour is $10\%$.

And that of gold colour is $5\%$.

Answer-(A)

The________ indicates the multiplier telling you the power of ten to which the two significant digits in color coding of the resistor  must be multiplied (or how many zeros to add).

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. 2nd band

  2. 3rd band

  3. 4th band

  4. last band

Show answer
Correct Option: B
Explanation:

The 3rd band indicates the multiplier telling the power of ten to which the two significant digits in color coding of the resistor must be multiplied.


Answer-(B)

Which color band  in the color coding of a resistor has the multiplier $10^{-1}$?

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. Silver

  2. Gold

  3. Yellow

  4. Orange

Show answer
Correct Option: B
Explanation:
The $gold$ colour has the color coding as the multiplier of $10^{-1}=0.1$.

These data need to be remembered.

Answer-(B)

Which of the following is true for carbon resistors?

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. Resistance value does not get changed by change in temperature

  2. Current carrying capacity and hence power wattage are limited to about $50$ Watts.

  3. It has low-temperature coefficient value.

  4. Stability and reliability are very good.

Show answer
Correct Option: C
Explanation:

$A\rightarrow$ Resistance value of carbon resistor with change in temperature it has negative thermal coefficient.

$B\rightarrow$ Carbon resistors are not current carrying capacitor.
$C\rightarrow$ Carbon has low temperature coefficient value i.e. higher the temperature, lower the resistivity.
$D\rightarrow$ Because of low stability of resistance value this type of resistors are not suitable.

Red,orange,black are the color bands on resistors.Find its resistance?

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. $23\Omega \pm20$ %

  2. $25\Omega \pm10$ %

  3. $32\Omega \pm20$ %

  4. $53\Omega \pm15$ %

Show answer
Correct Option: A
Explanation:

For first two significant digits of resistance ,  we see the first two colours .

And, third color signifies the multiplier.

Here, red color means digit $2$ and orange color means $3$.
And for multiplier, black colour means multiplier of $1$.

Hence resistance is $(23\times 1)=23\Omega$

Since , nothing is said about fourth color, we can check answer from the calculated resistance.

Answer-(A)

Brown,black and gold is the color band on the resistor,find its resistance?

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. $10\times 10^{-2}\Omega$

  2. $1\Omega$

  3. $100 \Omega$

  4. $10\times 10^{0}\Omega$

Show answer
Correct Option: B
Explanation:

The first two colours are brown and black.


For first two significant digits we need to consider digits signified by first two colours.
And, brown colour signifies $1$, and black colour signifies $0$.
And for multiplier the third colour is considered which is here gold meaning $0.1$.

Hence, resistor is $10\times 0.1=1\Omega$

Answer-(B)

A carbon resistance with color band is $200\Omega$. If red band is replaced by green band then the new resistance is:

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. $500\Omega$

  2. $300\Omega$

  3. $400\Omega$

  4. $100\Omega$

Show answer
Correct Option: A
Explanation:

Significant figure of red band is $2$ and for green is $5$
 so new resistance $500 \Omega$

Which of the following is not the advantage of Carbon resistors?

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. It is small in size and is light in weight.

  2. It has low-temperature coefficient value.

  3. Using it high-value resistor can easily be made.

  4. It has high power rating with a low tolerance value.

Show answer
Correct Option: D
Explanation:

Advantages of carbon resistors are:

  1. It is small in size and is light in weight.
  2. It has low temperature coefficient that means small change in temperature leds to high resistivity change.
  3. It provides greater resistance, so using this high value resistor can easy be made.
  4. They have low to medium type power rating of range $0.125w$ to $5w$.
  5. They have high tolerance values such as $\pm 5\%,\pm 10\%,$ and $\pm 20\%$.
Hence statement $(D)$ is wrong.


The carbon resistor has three orange bands. The maximum value of resistance offered by the resistor will be __________.

physics electric current through conductors carbon resistance and colour codes for carbon resistance carbon resistors and their colour coding resistors

  1. $39.6k\Omega $

  2. $49.6k\Omega $

  3. $33k\Omega $

  4. $26.4k\Omega $

Show answer
Correct Option: C
Explanation:
The resistance can be calculated with a help of the colour coding chart.
The colour of the first band indicates the first significant figure, the colour of the second band indicates the second significant figure and the colour of the third band indicates the multiplier to be used. 
Thus, the resistance of a carbon resistor with three orange bands would be:
3 (orange) 3(orange) x 1000 (orange) = 33,000 ohms

The maximum value of resistance $=33\times { 10 }^{ 3 }\Omega =33k\Omega $