Resistivities of copper, constantan and silver are 1.7 × 10 − 8 Ω m , 39.1 × 10 − 8 Ω m and 1.6 × 10 − 8 Ω m respectively. Which has the best conductivity?

Conductivity = 1 Resistivity As silver has the lowest resistivity, so it has the best conductivity.

There are two conductors A and B of the same material, having lengths l and 2 l ; and having radii r and r 2 respectively. What is the ratio of their resistances?

Two wires are same material. Length of 1st wire=l Length of 2nd wire=2l R 1 R 2 = l 1 l 2 ⋅ r 2 r 1 2 = l 2 l r 2 r 2 = 1 8 = 1 : 8 .

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What is the cause of resistance of a conductor?

Important Questions on Current Electricity

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IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 10

Resistivities of copper, constantan and silver are

1.7 \times 10^{- 8} Ω m

39.1 \times 10^{- 8} Ω m

and

1.6 \times 10^{- 8} Ω m

respectively. Which has the best conductivity?

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New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 11

A large number of free electrons are present in metals. Why is there no current in the absence of electric field across it?

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New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 12

Two wires of equal lengths, one of copper and the other of manganin have the same resistance. Which wire will be thicker?

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New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 13

If a wire is stretched to double its original length without loss of mass, how will the resistivity of the wire be influenced?

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New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 14

Two wires of equal cross-sectional area, one of copper and other of manganin have the same resistance. Which one will be longer?

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New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 15

There are two conductors

A

and

B

of the same material, having lengths

l

and

2 l

; and having radii

r

and

\frac{r}{2}

respectively. What is the ratio of their resistances?

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IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 16

Two wires

A

and

B

are of same metal, have the same area of cross-section and have their lengths in the ratio

2 : 1

. What will be the ratio of currents flowing through them respectively when the same potential difference is applied across the length of each of them?

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IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>VERY SHORT ANSWER CONCEPTUAL PROBLEMS>Q 17

Two wires $A$ and $B$ of the same metal and of the same length have their areas of cross-section in the ratio of $2 : 1$ . If the same potential difference is applied across each wire in tum, what will be the ratio of the currents flowing in $A$ and $B$ ?

What is the cause of resistance of a conductor?

Important Questions on Current Electricity

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