Tag: resistors

Questions Related to resistors

Which resistor is difficult to make of having a value less than about 2 Ohms? 

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

  1. Iron Resistor

  2. Carbon Resistor

  3. Wire wound Resistor

  4. Both b and c

Show answer
Correct Option: B
Explanation:

Carbon resistor is difficult to make of having a value less than about $20 $Ohms because they have ability to withstand high energy pulses, when current flow through the carbon composition body conducts the energy . So carbon resistor can be made with a higher resistance 

Resistors are generally colour coded to:

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

  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

Show answer
Correct Option: C
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.

Which of the following is not true for wire wound resistor?

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

  1. It has a lower order of stability and reliability.

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

  3. Easy to make wire wound resistor of value 0.01 Ohm.

  4. It is not suitable for high-frequency circuits.

Show answer
Correct Option: A
Explanation:
A wire wound resistor is an electrical passive component that limits current. The resistive element exists out of an insulated metallic wire that is winded around a core of non-conductive material. The wire material has a high resistivity, and is usually made of an alloy such as Nickel-chromium (Nichrome) or a copper-nickel-manganese alloy called Manganin. Common core materials include ceramic, plastic and glass. 
It has a lower order of stability and reliability  is not true for wire wound resistor

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

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

  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. $1.0 \times 10^7 \pm 10\%$

Show answer
Correct Option: B
Explanation:

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

Which of the following is not the disadvantage of wire wound resistor?

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

  1. It has a big size which is not suitable for many of the applications.

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

  3. Resistance value gets changed by a change in temperature, humidity etc.

  4. It is not suitable for high-frequency circuits.

Show answer
Correct Option: C
Explanation:

In wired resistors are mainly produced with alloys, since pure metal has a high temperature co-efficient.

Due to alloy temperature co-efficient of wire wound resistor is very low.
Therefore it is very less effected by temperature change.

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

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

  1. $2.2$

  2. $2200$

  3. $\left( 2200\pm 20\% \right) $

  4. $1.76$ to $2.64$

Show answer
Correct Option: C
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.

Which color band  in the color coding of a resistor has the tolerance $\pm2$%?

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

  1. Orange

  2. Black

  3. Silver

  4. Red

Show answer
Correct Option: D
Explanation:

Red color band in the color coding of a resistor has the tolerance of $\pm2\%$

Carbon resistors are of two types :

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

  1. composition type resistor and film type resistor

  2. rheostat and film type resistor

  3. rheostat and variable resistor

  4. composition type resistor and rheostat

Show answer
Correct Option: A
Explanation:
Carbon resistors are of two types  composition type resistor and film type resistor.

There are a number of different types of fixed resistor:

Carbon composition: These types were once very common, but are now seldom used. 

Carbon film: This resistor type is formed by "cracking" a hydrocarbon onto a ceramic former.

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

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

  1. Last two color bands

  2. First two color bands

  3. Last color band only

  4. First color band only

Show answer
Correct Option: B
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.

In the 5 band color resistor,which color bands are considered as significant digits?

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

  1. First band only

  2. First three bands

  3. First two bands

  4. Last band

Show answer
Correct Option: B
Explanation:

A 5-bandcolor resistor is represented as

$R=abc\times d\pm e\%$
Where, $a$ represents the $1^{st}$ significant digit, which is the first band color of resistor.
$b$ represents the $2^{nd}$ significant digit, which is the second band color of resistor.
$c$ represents the $3^{rd}$ significant digit, which is the third band color of resistor.
$d$ represents the $4^{th}$ significant digit, which is the fourth band color of resistor and this is the multiplier value used in formula.
$e$ represents the $5^{th}$ significant digit, which is the fifth band color of resistor and this is the tolerance value of resistor.