Explore topic-wise InterviewSolutions in Current Affairs.

Question 113(ii)

Sunscreens block harmful ultraviolet (UV) rays produced by the sun. Each sunscreen has a Sun Protection Factor (SPF) that tells you how many minutes you can stay in the sun before you receive one minute of burning UV rays. e.g. If you apply sunscreen with SPF 15, you get one minute of UV rays for every 15 minutes you stay in the sun.

- Suppose, a sunscreen allows 25% of the sun's UV rays.

(a) What fraction of UV rays does this sunscreen block? Give your answer in lowest terms.

(b) Use your answer from part (a) calculate this sunscreen's SPF. Explain how you found your answer?

Which one of the following has a center of gravity outside?

When some force is applied on a body of mass $2kg$, its velocity changes from 10 m/s to 20 m/s. The work done is .

Mass of a body is increased by 49 times. What should be done to the velocity to maintain the same KE.

A solution of urea (mol. mass $56{\text{g mol}}^{-1}$) boils at $100$. ${18}^0\text{C}$ at the atmospheric pressure. If $K_f\text{and}{K}_b$ for water are $1.86$ and $0.512{\text{K kg mol}}^{-1}$ respectively, the above solution will freeze at :

State how are the two resistors joined with a battery in each of the following cases when:
(a) Same current flows in each resistor,
(b) Potential difference is same across each resistor,
(c) equivalent resistance is less than either of the two resistances, and
(d) Equivalent resistance is more than either of the two resistances.

The self inductance of a closed-packed coil is $8\text{mH}$. A current of $5\text{mA}$ is passed through it. Find the magnetic flux per unit turn of the coil, if it has $100$ turns.

Calculate the position of the fulcrum at which a meter rule of mass 20 gf can be balanced when three weights 50 gf, 10 gf & 200 gf are applied at 20 cm, 40 cm & 90 cm marks respectively.

An object is placed at a distance of 20 cm in front of a concave lens of focal length 20 cm. Find :

(a) the position of image, and

(b) the magnification of image.

Why AC is more dangerous than DC?

A block of mass 50 kg is pulled up a slope with constant speed by applying an external force of 20 kgf parallel to the slope. The block moves through a distance of 4 m along the slope.

i) What is the work done by the external applied force?

ii) What is the energy stored when it reaches the vertical height of 3m (g = 10m/s²)

Dispersion without deviation is produced by two thin (small angled) prisms which are combined. One prism has angle $6^{\circ }$ and refractive index $1.52$. If the other prism has an angle $4^{\circ }$, what is its refractive index ?

Explain briefly, how rainwater harvesting is done from open spaces around the buildings in city areas. ​​​​

The energy released per fission reaction of ${\text{U}}^{235}$ is $200\text{MeV}$. Find the energy released by the fission of $1\text{g}$ of ${\text{U}}^{235}$.

$(\text{Avogadro number},N_A=6.023\times {10}^{23})$

Compare refraction in glass slab and in glass prism .

State the main function of the following:

Vitreous humour

Three resistors are connected to a 12 V battery as shown in the figure given below:

The potential difference across the parallel combination of 6 ohm and 12 ohm resistor is:

A real image of half the size of the object is obtained in a concave mirror with a radius of curvature of $40\text{cm}$. The distance of the object and that of its image from the mirror will be ______ and ______ respectively.

If the light moving in a straight line bends by a small but fixed angle, it may be the case of

1. 1512.95

Question 16

The weight of a person on a planet A is about half that on the earth. He can jump upto 0.4 m height on the surface of the earth. How high he can jump on the planet A?

Real, inverted and enlarged image will be formed in case of:

An infinite wire carries a current $I$. An $S$ shaped conducting rod of two semicircles each of radius $r$ is placed at angle $\theta$ to the horizontal as shown below. The centre of the conductor is at a distance $d$ from the wire. If rod translates parallel to the wire with velocity $u$, calculate the emf induced across the ends of the rod.

50 g of ice 0${}^{\circ }C$ is added to 300 g of a liquid at 30${}^{\circ }C$. What will be the final temperature of the mixture when all the ice has melted? The specific heat capacity of the liquid is 2.65 $J{g}^{-1}{}^{\circ }{C}^{-1}$ while that of water is 4.2 $J{g}^{-1}{}^{\circ }{C}^{-1}$ . Specific latent heat of fusion of ice = 336 J $g^{-1}$.