Tag: electric current through conductors

Questions Related to electric current through conductors

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

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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

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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

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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.

Which color band in the resistor is having highest tolerance?

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

  1. Violet

  2. Green

  3. Blue

  4. None of the above

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Correct Option: B
Explanation:

Tolerance level of

Green:$0.5\%$
Blue:$0.25\%$
Violet:$0.1\%$
Hence green is having highest tolerance.

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

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

  1. Exactly 100

  2. 95 to 105

  3. 90 to 110

  4. 80 to 120

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Correct Option: B
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 $105\Omega$ 

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

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

  1. 900 ohm and 1100 ohm

  2. 900 ohm and 1010 ohm

  3. 990 ohm and 1010 ohm

  4. 900 ohm and 1000 ohm

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Correct Option: A
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.

The color coding of  earth, live and neutral wire respectively is

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

  1. Green, Red, black

  2. Red, Green, Black

  3. Red, Black, Green

  4. None of the above

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Correct Option: A
Explanation:

The electric power line enters our house through three wires- namely the live wire, the neutral wire and the earth wire. To avoid confusion we follow a colour code for insulating these wires. The red wire is the live wire, and the black wire is neutral. The earth wire is given green plastic insulation.
The colour coding of wires is green for earth red for live and black for neutral.

According to international convention of colour coding in a wire

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

  1. Live is red, neutral is yellow and earth is green

  2. Live is red, neutral is green and earth is black

  3. Live is brown, neutral is blue and earth is black

  4. Live is red, neutral is black and earth is green

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Correct Option: D
Explanation:

According to international color coding system in Old colors red is live ( or phase) black is neutral, green/ yellow is earth 
and in New colors brown is live, blue is neutral and green/ yellow is earth.

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

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

  1. $10 \Omega$

  2. $100 m \Omega$

  3. $0.1 k\Omega$

  4. 100 + 5%

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Correct Option: C
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 $.

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

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

  1. $2.5 \pm 10$% ohm

  2. $3.5 \pm 5$% ohm

  3. $3.5 \pm 10$% ohm

  4. $350 \pm 10$% ohm

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Correct Option: C
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.