41.

A galvanometer of resistance 25 Ω shows a deflection of 5 divisions when a current of 2 mA is passed through it. If a shunt of 4 Ω is connected and there are 20 divisions on the scale, then the range of the galvanometer is

• 1 A

• 58 A

• 58 mA

• 30 mA

The total charge induced in a conducting loop when it is moved in magnetic field depends on

• the rate of change of magnetic flux

• initial magnetic flux only

• the total change in magnetic flux

• final magnetic flux only

The length of a given cylindrical wire is increased by 150%. Due to the consequent decrease in diameter the change in the resistance of the wire will be

• 200 %

• 525 %

• 300 %

• 400 %

An ideal solenoid having 5000 turns/m has an aluminium core and carries a current of 5A. If χ_Al = 2.3 × 10^-5,  then the magnetic field developed at centre will be

• 0.031 T

• 0.048 T

• 0.027 T

• 0.050 T

A capacitor is charged and then made to discharge through a resistance. The time constant is t. In what time will the potential difference across the capacitor decrease by 10 %?

• τ ln 0.1

• τ ln 0.9

• τ ln$\frac{10}{9}$

• τ ln$\frac{11}{10}$

A fish rising vertically to the surface of water in a lake uniformly at the rate of 2 m/s observes a kingfisher diving vertically towards the water at a rate of 10 m/s. If refractive index of water n = $\frac{4}{3}$ what will be the actual velocity of the kingfisher

• 10 m/s

• 8 m/s

• 6 m/s

• 9 m/s

A block having 12g of element is placed in a room. This element is a radioactive element with half-life of 15 yr. After how many years will there be just 1.5 g of the element in the box?

• 40 yr

• 45 yr

• 20 yr

• 15 yr

A square wire of side 2.0 cm is placed 20 cm in front of a concave mirror of focal length 10 cm with its centre on the axis of the mirror and its plane normal to the axis. The area enclosed by the image of wire is

• 7.5 cm²

• 6 cm²

• 2 cm²

• 4 cm²

A quarter cylinder of radius R and refractive index 1.5 is placed on a table. A point object P is kept at a distance ofmR from it as shown in figure. For what value of m for which a ray from P will emerge parallel to the table?

• $\frac{2}{3}$

• $\frac{3}{2}$

• $\frac{4}{3}$

• $\frac{3}{4}$

The graph $\frac{1}{\mathrm{\lambda }}$ and stopping potential (V) of three metals having work function ${\mathrm{\varphi }}_1 , {\mathrm{\varphi }}_2 \mathrm{and} {\mathrm{\varphi }}_3$ in an experiment of photoelectric effect is plotted as shown in the figure. Which one of the following statement is/are correct? [Here λ is the wavelength of the incident ray ]

(i) Ratio of work functions  = 1 : 2 : 4

(ii) Ratio of work functions ${\mathrm{\varphi }}_1 : {\mathrm{\varphi }}_2 : {\mathrm{\varphi }}_3$ = 4 : 2 : 1

(iii) tanθ ∝ $\frac{\mathrm{h} \mathrm{c}}{\mathrm{e}}$, where h = Planck's constant, c = speed of light

(iv)The violet colour-light can eject photoelectrons from metals 2 and 3

• (i), (iii)

• (i), (iv)

• (ii), (iii)

• (i), (ii) and (iv)