Answer: a) 7.5o The distance between the refracting surfaces is negligible with thin prisms, thus the prism angle (A) is very small. Because A = r1 + r2, if A is tiny, both r1 and r2 will be little...

### A ray of light incident at an angle θ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5o and the prism is made of a material of refractive index 1.5, the angle of incidence is

### First, a set of n equal resistors of R each are connected in series to a battery of emf E and internal resistance R. A current I is observed to flow. Then the n resistors are connected in parallel to the same battery. It is observed that the current is increased 10 times. What is ‘n’?

The current is represented as I = E/R+nR when the resistors are connected in series. Current is expressed as 10I = E/(R+R/n) when the resistors are connected in parallel. We get n = 10 by solving...

### In the figure, two positive charges q2 and q3 fixed along the y-axis, exert a net electric force in the +x direction on a charge q1 fixed along the x-axis. If a positive charge Q is added at (x,0) the force on q1 a) shall increase along the positive x-axis b) shall decrease along the positive x-axis c) shall point along the negative x-axis d) shall increase but the direction changes because of the intersection of Q with q2 and q3

the correct option is a) shall increase along the positive x-axis.

### Mars has approximately half of the earth’s diameter. When it is closer to the earth it is at about ½ AU from the earth. Calculate at what size it will disappear when seen through the same telescope.

$D_{mars}/D_{earth}=1/2$ Also, $D_{earth}/D_{sun}=1/100$ So, $D_{mars}/D_{sun}=1/2\times 1/100$ At 1AU, the sun’s diameter is = (1/2) degree Therefore, diameter of mars will be = (1/400) degree At...

### a) How many astronomical units (AU) make 1 parsec?

b) Consider the sun like a star at a distance of 2 parsec. When it is seen through a telescope with 100 magnification, what should be the angular size of the star? Sun appears to be (1/2) degree from the earth. Due to atmospheric fluctuations, eye cannot resolve objects smaller than 1 arc minute.

a) 1 parsec is the distance at which 1 AU long arc subtends an angle of 1s, according to the definition. Using the definition, we can write, 1 parsec = (3600)(180)/π AU = 206265 AU = 2 × 105 AU b)...

### Name the device used for measuring the mass of atoms and molecules.

Mass spectrograph is a tool for determining the mass of atoms and molecules.

### Which of the following ratios express pressure?

a) Force/area

b) Energy/volume

c) Energy/area

d) Force/volume

Correct answers are a) force/area and b) energy/volume

### A particle is in linear simple harmonic motion between two points, A and B, apart. Take the direction from to as the positive direction and give the signs of velocity, acceleration and force on the particle when it is

(a) at away from A going towards , and

(b) at away from B going towards .

(a) Positive, Positive, Positive From the end $A$, the particle is travelling toward point 0. This motion is going from $A$ to $B$, which is the standard positive direction. As a result, the...

### A mild steel wire of length and cross-sectional area is stretched, well within its elastic limit, horizontally between two pillars. A mass of is suspended from the mid-point of the wire. Calculate the depression at the midpoint.

Water pressure at the bottom is given as, $p=1000 a t m=1000 \times 1.013 \times 10^{5}$ Pa $p=1.01 \times 10^{8} \mathrm{~Pa}$ Initial volume of the steel ball is given as $V=0.30 \mathrm{~m}^{3}$...