Three copper wires have lengths and cross-sectional areas as ( l , A ) , ( 2 l , A 2 ) and ( l 2 , 2 A ) . Resistance is minimum in

Wire of cross-sectional area 2 A

Wire of cross-sectional area A 2

Three copper wires have lengths and cross-sectional areas as ( l , A ) , ( 2 l , A 2 ) and ( l 2 , 2 A ) . Resistance is minimum in

Wire of cross-sectional area 2 A

A carbon resistor of 47 ± 4.7 kΩ is to be marked with rings of different colours for its identification. The colour code sequence will be:

Yellow - Violet - Orange - Silver

Violet - Yellow - Orange - Silver

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 19

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Three copper wires have lengths and cross-sectional areas as $(l, A), (2 l, \frac{A}{2})$ and $(\frac{l}{2}, 2 A)$ . Resistance is minimum in

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Important Questions on Current Electricity

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 20

The resistance of a wire of cross-section

a

and length

l

is

R

ohm. The resistance of another wire of the same material and of the same length but cross-section

4 a

will be

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 21

The resistance of wire is

R

ohm. The wire is stretched to half of its diameter. The resistance of the wire will now be

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 22

If a wire of resistance

R

is stretched to double of its length, then the new resistance will be

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 23

All the edges of a block in cuboidal shape with parallel faces are unequal. Its longest edge is twice its shortest edge. The ratio of the maximum to minimum resistance between parallel faces is: $(a > b > c)$

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 24

Read the following statements carefully
$Y$ : The resistivity of semiconductors decreases with an increase in temperature.

Z

: In a conducting solid, the rate of collisions between free electrons and ions increases with an increase of temperature.
Select the correct statement (s) from the following

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 25

The dimensions of a block are

1 cm \times 1 cm \times 100 cm

. If the specific resistance of its material is

2 \times 10^{- 7}

ohm

\times

metre

, then the resistance between the opposite rectangular faces is

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Alpha Question Bank for Medical: Physics>Chapter 24 - Current Electricity>Exercise-1>Q 26

A conductor with a rectangular cross-section has dimensions $(4 a \times 2 a \times a)$ as shown in the figure. Resistance across $A B$ is $x$ , across $C D$ is $y$ , and across $E F$ is $z .$ Then,