# JEE Mains Evening Question Paper 2019 Physics Part 4 Download all the papers for 2019 Exam

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Q-11 A parallel plate capacitor with square plates is filled with four dielectrics of dielectric constants arranged as shown in the figure. The effective dielectric constant K will be:

Options:-

1.

2.

3.

4.

Answer: 4

Explanation:-

In the same way we get, >

……………….. (i)

Now if …………. (ii)

On comparing equation (i) and (ii), we get

This does not match with any of the options so probably they have assumed the wrong combination

However this is one of the four options.

It must be a “Bonus” logically but of the given options probably they might go with (4)

Q-12 A rod of length 50 cm is pivoted at one end. It is raised such that if makes an angle of from the horizontal as shown and released from rest. Its angular speed when it passes through the horizontal (in sad) will be

Options:-

1.

2.

3.

4.

Answer: 1

Explanation:-

Kinetic energy of rotation-

Where in

Imoment of inertia about axis of rotation

w angular velocity

A rod of length 50 cm is pivoted at one end.

Work done by gravity from initial to final point

…………. (1)

By work energy theorem

…………… (2)

rad/sec