JEE Main 2021 (Online) 17th March Morning Shift | Current Electricity Question 173 | Physics

A current of 10A exists in a wire of cross-sectional area of 5 mm² with a drift velocity of 2 $$\times$$ 10^$$-$$3 ms^$$-$$1. The number of free electrons in each cubic meter of the wire is ___________.

625 $$\times$$ 10²⁵

1 $$\times$$ 10²³

2 $$\times$$ 10²⁵

2 $$\times$$ 10⁶

JEE Main 2021 (Online) 16th March Evening Shift

MCQ (Single Correct Answer)

-1

A resistor develops 500 J of thermal energy in 20 s when a current of 1.5A is passed through it. If the current is increased from 1.5A to 3A, what will be the energy developed in 20 s.

1000 J

2000 J

1500 J

500 J

JEE Main 2021 (Online) 16th March Morning Shift

MCQ (Single Correct Answer)

-1

A conducting wire of length 'l', area of cross-section A and electric resistivity $$\rho$$ is connected between the terminals of a battery. A potential difference V is developed between its ends, causing an electric current.

If the length of the wire of the same material is doubled and the area of cross-section is halved, the resultant current would be :

$$4{{VA} \over {\rho l}}$$

$${3 \over 4}{{VA} \over {\rho l}}$$

$${1 \over 4}{{VA} \over {\rho l}}$$

$${1 \over 4}{{\rho l} \over {VA}}$$

JEE Main 2021 (Online) 26th February Evening Shift

MCQ (Single Correct Answer)

-1

A wire of 1$$\Omega$$ has a length of 1 m. It is stretched till its length increases by 25%. The percentage change in resistance to the nearest integer is :

76%

12.5%

25%

56%

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