Physics

Current Electricity and Circuits

377 Questions

Current electricity and circuits questions cover resistors, EMF, internal resistance, and power calculations in series and parallel configurations. Solving these builds a strong understanding of electrical principles and circuit analysis. These physics problems are highly relevant for technical and science aptitude tests.

Resistor combinationsPower dissipationEMF and internal resistanceAC circuit analysisOperational amplifiers

Current Electricity and Circuits Questions

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

Resistors are generally colour coded to:

  1. Indicate the type of the circuit in which they are to be used

  2. Identify whether they are ohmic or non-ohmic

  3. Determine their values in ohm

  4. Determine whether they are wire wound or composition resistors
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Components and wires are coded with colors to identify their value and function. The colors brown, red, green, blue, and violet are used as tolerance codes on 5-band resistors only.

So,Resistors are generally colour coded to determine their values in ohm.
Therefore, C is correct option.

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

A given resistor has the following colour scheme of the various strips on it : Brown, black, green and silver. Its value in ohm is :

  1. $1.0 \times 10^4 \pm 10\%$
  2. $1.0 \times 10^5 \pm 10\%$
  3. $1.0 \times 10^6 \pm 10\%$
  4. $1.0 \times 10^7 \pm 10\%$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Numbers attached for brown, black, green and silver are $1, 0, 5, \pm10\%$. Therefore the resistance of given resistor
$= 10 \times 10^5\  \Omega  \pm 10\%$.

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

There are three red colored bands on a carbon resistor. What is its resistance ?

  1. $2.2$
  2. $2200$
  3. $\left( 2200\pm 20\% \right) $
  4. $1.76$ to $2.64$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to the color code of resistance,

code of red $=2$
code of red $=2$
code of red $=2$
The resistance of carbon resistor, $22\times 10^2 \pm20$%
$2200\pm20$%
The correct option is C.

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

________  represents the most significant digits of the resistance value in finding the  resistance of carbon resistor.

  1. Last two color bands

  2. First two color bands

  3. Last color band only

  4. First color band only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since first and second color bands has higher multiplier, they represents the most significant digits of the resistance value in finding the  resistance of carbon resistor.

Therefore, B is correct option.

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

The sequence of bands in carbon resistor are brown, black, brown and gold, the value of resistance is (in $\Omega$)

  1. Exactly 100

  2. 95 to 105

  3. 90 to 110

  4. 80 to 120
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

${1^{st}}Band:Brown - 1$

${2^{nd}}Band:Black - 0$
$Multiplier:Brown -  \times 10\Omega $
$Tolerance: \pm 5\% $
${\rm{Resistor }}value:{\rm{ }}100\Omega  \pm 5\% $
$95$ to $105\Omega$ 

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

A resistor with the color coded value of 1000 ohms and 10% tolerance can have an actual resistance between

  1. 900 ohm and 1100 ohm

  2. 900 ohm and 1010 ohm

  3. 990 ohm and 1010 ohm

  4. 900 ohm and 1000 ohm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

color coding gives a range in which value of resister lies.


Actual resistance $R=1000\pm 10$%
$ R=1000\pm 1000\times \frac { 10 }{ 100 } \ R=1000\pm 100$
Value of R is between 900 to 1100ohms.

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

The colour code of a resistor is brown, black and brown. Then the value of resistance is .....

  1. $10 \Omega$
  2. $100 m \Omega$
  3. $0.1 k\Omega$

  4. 100 + 5%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Answer is C.

Carbon-composition and carbon film resistors are too small to have the resistance value printed on their housings. Therefore, bands of color are used to represent the resistance value.
The first and second band represents the numerical value of the resistor, and the color of the third band specify the power-of-ten multiplier. The color bands are always read from left to right starting with the side that has a band closer to the edge.
Hence, for a brown, black, brown color code of a resistor. The resistance value is 100 ohms, that is, $0.1k\Omega $.

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

Color of the four strips of carbon resistor are respectively orange, green, golden, silver. Then its resistance is :

  1. $2.5 \pm 10$% ohm
  2. $3.5 \pm 5$% ohm
  3. $3.5 \pm 10$% ohm
  4. $350 \pm 10$% ohm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Code of orange$=3$


Code of green $=5$


Code of golden $=\div10$

Code of silver , Tolerance$=\pm 10$%

The resistance of wire, $R=3.5\pm10$% $ohm$

The correct option is C.

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

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

  1. $23\Omega \pm20$ %
  2. $25\Omega \pm10$ %
  3. $32\Omega \pm20$ %
  4. $53\Omega \pm15$ %
Reveal answer Fill a bubble to check yourself
A Correct answer
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)

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

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

  1. $10\times 10^{-2}\Omega$
  2. $1\Omega$
  3. $100 \Omega$
  4. $10\times 10^{0}\Omega$
Reveal answer Fill a bubble to check yourself
B Correct answer
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)

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

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

  1. $500\Omega$
  2. $300\Omega$
  3. $400\Omega$
  4. $100\Omega$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

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

  1. $39.6k\Omega $
  2. $49.6k\Omega $
  3. $33k\Omega $
  4. $26.4k\Omega $
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $