Q. No.If the focal length of the objective lens is increased then the magnifying power of:
1.
microscope will increase but that of the telescope decrease.
2.
microscope and telescope both will increase.
3.
microscope and telescope both will decrease.
4.
microscope will decrease but that of the telescope will increase.
| 1. | \(\dfrac{R}{2(\mu_1-\mu_2)}\) | 2. | \(\dfrac{R}{(\mu_1-\mu_2)}\) |
| 3. | \(\dfrac{2R}{(\mu_2-\mu_1)}\) | 4. | \(\dfrac{R}{2(\mu_1+\mu_2)}\) |
For a normal eye, the cornea of the eye provides a converging power of \(40~\text{D}\) and the least converging power of the eye lens behind the cornea is \(20~\text{D}\). Using this information, the distance between the retina and the cornea-eye lens can be estimated to be:
1. \(2.5~\text{cm}\)
2. \(1.67~\text{cm}\)
3. \(1.5~\text{cm}\)
4. \(5~\text{cm}\)
When a biconvex lens of glass having a refractive index of \(1.47\) is dipped in a liquid, it acts as a plane sheet of glass. The liquid must have a refractive index:
| 1. | equal to that of glass. |
| 2. | less than one. |
| 3. | greater than that of glass. |
| 4. | less than that of glass. |
A ray of light is incident at an angle of incidence, \(i\), on one face of a prism of angle \(A\) (assumed to be small) and emerges normally from the opposite face. If the refractive index of the prism is \(\mu,\) the angle of incidence \(i\), is nearly equal to:
1. \(\mu A\)
2. \(\frac{\mu A}{2}\)
3. \(\frac{A}{\mu}\)
4. \(\frac{A}{2\mu}\)
A concave mirror of the focal length \(f_1\) is placed at a distance of \(d\) from a convex lens of focal length \(f_2\). A beam of light coming from infinity and falling on this convex lens-concave mirror combination returns to infinity. The distance \(d\) must be equal to:
1. \(f_1+f_2\)
2. \(-f_1+f_2\)
3. \(2f_1+f_2\)
4. \(-2f_1+f_2\)
The magnifying power of a telescope is \(9\). When it is adjusted for parallel rays the distance between the objective and eyepiece is \(20~\text{cm}\). The focal length of the lenses is:
1. \(10~\text{cm}, ~10~\text{cm}\)
2. \(15~\text{cm}, ~5~\text{cm}\)
3. \(18~\text{cm}, ~2~\text{cm}\)
4. \(11~\text{cm}, ~9~\text{cm}\)
| 1. | virtual, upright, height \(=0.5\) cm |
| 2. | real, inverted, height \(=4\) cm |
| 3. | real, inverted, height \(=1\) cm |
| 4. | virtual, upright, height \(=1\) cm |
| 1. | Difference between apparent and real depth of the pond |
| 2. | Mirage on hot summer days |
| 3. | Brilliance of the diamond |
| 4. | Working of optical fibre |
A ray of light travelling in a transparent medium of refractive index \(\mu\) falls on a surface separating the medium from the air at an angle of incidence of \(45^{\circ}\). For which of the following value of \(\mu\), the ray can undergo total internal reflection?
1. \(\mu = 1.33\)
2. \(\mu =1.40\)
3. \(\mu=1.50\)
4. \(\mu = 1.25\)
© 2024 GoodEd Technologies Pvt. Ltd.