Alternating Current — Physics STD 12 Science — Question

Permanent magnets should have:

The refractive index of water with respect to air is 4 / 3 and the refractive index of glass with respect to air is 3/2. The refractive index of water with respect to glass is

(a)

(b)

(c)

(d) 2

Figure here shows P and Q as two equally intense coherent sources emitting radiations of wavelength 20 m. The separation PQ is 5.0 m and phase of P is ahead of the phase of Q by 90^o. A, B and C are three distant points of observation equidistant from the mid-point of PQ. The intensity of radiations at A, B, C will bear the ratio

(a) 0 : 1 : 4

(b) 4 : 1 : 0

(c) 0 : 1 : 2

(d) 2 : 1 : 0

Five capacitors of 10 μF capacity each are connected to a d.c. potential of 100 volts  as shown in the adjoining figure. The equivalent capacitance between the points  A and B will be equal to

(a) 40 μF

(b) 20 μF

(c) 30 μF

(d) 10 μF

Two charges each equal to 2μC are 0.5m apart. If both of them exist inside vacuum, then the force between them is

(a) 1.89 N

(b) 2.44 N

(c) 0.144 N

(d) 3.144 N

The energy of a photon of light of wavelength 450 nm is

(a) 4.4

(b) 2.5

(c) 1.25

(d) 2.5

Two resistances of 400 W and  800 W are connected in series with 6 volt battery of negligible internal resistance.  A voltmeter of resistance 10,000 W is used to measure the potential difference across 400 W.  The error in the measurement of potential difference in volts approximately is

(a) 0.01

(b) 0.02

(c) 0.03

(d) 0.05

For which of the following particles will it be most difficult to experimentally verify the de-Broglie relationship?

We get __________ current through rectifier without simple filter.

Which metal is used to make ferromagnets ?