Angle of Elevation

Q. A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness $3\text{cm}$ and refractive index $1.5$ is placed over the mark. How should the microscope be moved to get the mark in focus again?

1. $1\text{cm}$ upward
2. $4.5\text{cm}$ downward
3. $1\text{cm}$ downward
4. $2\text{cm}$ upward

Q. The magnifying power of a compound microscope does not depend upon -

1. the focal length of the eyepiece.
2. the aperture of the objective lens.
3. tube length of the compound microscope.
4. None of the above

Q. In a simple microscope, if the final image is located at infinity then its magnifying power is; ($D$ is the least distance for distinct vision in the simple microscope)

1. $D/F$
2. $F/D$
3. $(1+D)/F$
4. $1$

Q. A simple microscope has a focal length of $25\text{cm}$. The maximum and minimum magnifying powers, that can be obtained are, respectively -

1. $3$ and $1$
2. $2$ and $1$
3. $3$ and $2$
4. $4$ and $2$

Q. A microscope is provided with a main scale graduated with 20 divisions in 1 cm and a vernier scale with 50 divisions on it of length same as of 49 divisions of main scale. Find the least count of the microscope.

Q. Assertion : If objective and eye lenses of a microscope are interchanged, it can work as a telescope.
Reason : The objective lens of a telescope has small focal length.

1. Both Assertion and Reason are true and Reason is correct explanation of Assertion
2. Both Assertion and Reason are true and Reason is not correct explanation of Assertion
3. Assertion is true but Reason is flase.
4. Assertion and Reason both are false

Q. Given below are two statements.

Assertion : If objective lens and eyepiece of a compound microscope are interchanged then it can work as telescope.

Reason : The objective lens of the telescope has small focal length.

Based on the above statements, choose the correct alternative.

1. Both assertion and reason are true and reason is a correct explanation of assertion.
2. Both assertion and reason are true, but reason is not a correct explanation of assertion.
3. Assertion is true, but reason is false.
4. Both assertion and reason are false.

Q. A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness $3\text{cm}$ and refractive index $1.5$ is placed over the mark. How should the microscope be moved to get the mark in focus again?

1. $1\text{cm}$ upward
2. $4.5\text{cm}$ downward
3. $1\text{cm}$ downward
4. $2\text{cm}$ upward

Q. Equal charges, $q$ each are placed at the vertices A and B of an equilateral triangle ABC of side $a$. The magnitude of electric intensity at the point C is:

1. $\frac{q}{4\pi {\epsilon }_0{a}^2}$
2. $\frac{\sqrt{2}q}{4\pi {\epsilon }_0{a}^2}$
3. $\frac{\sqrt{3}q}{4\pi {\epsilon }_0{a}^2}$
4. $\frac{2q}{4\pi {\epsilon }_0{a}^2}$

Q. A person suffering from myopia wishes to see a magnified image of an object, through a compound microscope. If the microscope forms the final image at infinity, the person should view the image,

1. with his/her spectacle removed.
2. using his/her spectacle.
3. either using his/her spectacle or without it.
4. Insufficient information

Q. An electron microscope is superior to an optical microscope in terms of:

1. quickness of observation
2. being easy to handle
3. low cost
4. having better resolving power

Q. A ball of mass $1kg$ is at rest in position $P$ by means of two light strings $OP$ and $RP$. The string $RP$ is now cut and the ball swings to position $Q$. If $\theta ={45}^o$. Find the ratio of tensions in the strings in positions $OP$ (when $RP$ was not cut ) and $OQ$ (when $RP$ was cut). Take $g=10m/s^2$

1. $5\sqrt{2}$
2. $2$
3. $3$
4. $1.5$