46789.A diver at a depth of 12 m in water $\\mu=\\dfrac{4}{3}$ sees the sky in a cone of semiverticale
angle :
angle :
$\sin^{-1}(\dfrac{4}{3})$
$\tan^{-1}(\dfrac{4}{3})$
$\sin^{-1}(\dfrac{3}{4})$
90°
46790.A particle performs a uniform circular motion with an angular momentum L. If the frequency of
the particle s motion is doubled and its KE is halved, the angular momentum becomes
the particle s motion is doubled and its KE is halved, the angular momentum becomes
4 L
0.5 L
2 L
0.25 L
46791.A radioactive substance has a half-life of 60 minutes. During 3 hour, the fraction of atoms that
have decayed would be
have decayed would be
12.5%
25.1%
8.5%
87.5%
46792.A convex lens of focal length 30 cm produces 5 times magnified real image of an
object. What is the object distance ?
object. What is the object distance ?
36 cm
25 cm
30 cm
150 cm
46793.The frequency of oscillation of current in the inductance is
$\dfrac{1}{3\sqrt{LC}}$
$\dfrac{1}{6\pi\sqrt{LC}}$
$\dfrac{1}{\sqrt{LC}}$
$\dfrac{1}{2\pi\sqrt{LC}}$
46794.1.56 X $10^5$J of heat is conducted through a 2 $m^2$ wall of 12 cm thick in one hour.
Temperature difference between the two sides of the wall is 20 °C.
The thermal conductivity of the material of the wall is (in W $m^{-1} K^{-1}$)
Temperature difference between the two sides of the wall is 20 °C.
The thermal conductivity of the material of the wall is (in W $m^{-1} K^{-1}$)
0.11
0.13
0.15
1.2
46795.A stone of relative density K is released from rest on the surface of a lake. If viscous
effects are ignored, the stone sinks in water with an acceleration of
effects are ignored, the stone sinks in water with an acceleration of
g(1 – k)
g(1+K)
g$(1-\dfrac{1}{k})$
g$(1+\dfrac{1}{k})$
46796.A block B is pushed momentarily along a horizontal surface with an initial velocity v. If $\\mu$ is
the coefficient of sliding friction between B and the surface, block B will come to rest after a time
the coefficient of sliding friction between B and the surface, block B will come to rest after a time
$\dfrac{v}{g\mu}$
$\dfrac{g\mu}{v}$
$\dfrac{g}{v}$
$\dfrac{v}{g}$
46797.A body falling from a height h travels 40 m in the last two seconds of its fall to ground. The
height h in metres is (use g = 10 $ms^{-2}$)
height h in metres is (use g = 10 $ms^{-2}$)
80
60
45
40
46798.A lens is placed between a source of light and a wall. It forms images of area A1 and A2 on
the wall, for its two different positions. The are of the source obtained is
the wall, for its two different positions. The are of the source obtained is
$\frac{(A_1 + A_2)}{2}$
$\sqrt{A_1A_2}$
$[a^{-1}_{1} + a^{-1}_{2}]^{-1}$
$[\frac{\sqrt{A_1}+\sqrt{A_2}}{2}]^2$
46799.A body is thrown horizontal from the top of a tower and strikes the ground after three seconds
at an angle of 45° with the horizontal. Then find the height of the tower
at an angle of 45° with the horizontal. Then find the height of the tower
30m
45m
50m
55m
46800.The gravitational field due to a mass distribution is I= $\\dfrac{C}{x^{2}}$ in x direction. Here, C is constant.
Taking the gravitational potential to be zero at infinity, potential at x is:
Taking the gravitational potential to be zero at infinity, potential at x is:
$\dfrac{2C}{x}$
$\dfrac{C}{x}$
$\dfrac{2C}{x^2}$
$\dfrac{C}{2x^2}$
46801.Figure shows a rectangular coil of cross-sectional area A placed in a uniform magnetic field B
directed along z-axis. The torque on coil is
directed along z-axis. The torque on coil is
ABI along +ve Y-axis
ABI along -ve Y-axis
ABI along +ve X-axis
zero
46802.The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is -20°C,
the temperature of the surroundings to which it rejects heat is
the temperature of the surroundings to which it rejects heat is
31°C
41°C
11°C
21°C
46803.In an LCR circuit, the potential difference between the terminals of the inductor is 60 V,
between the terminals of capacitor is 30 V and that between the terminals of resistor is 40 V.
The supply voltage is
between the terminals of capacitor is 30 V and that between the terminals of resistor is 40 V.
The supply voltage is
25 V
50 V
100 V
130 V
46804.Assertion : Microwave have more energy than the radiowaves.
Reason : Energy E = $hc/\\lambda$.
A. Both, Assertion and Reason are true and the Reason is correct explanation of the Assertion.
B. Both, Assertion and Reason are true but the Reason is not correct explanation of the Assertion.
C. Assertion is true but the Reason is false.
D. Both, Assertion and Reason are false.
Reason : Energy E = $hc/\\lambda$.
A. Both, Assertion and Reason are true and the Reason is correct explanation of the Assertion.
B. Both, Assertion and Reason are true but the Reason is not correct explanation of the Assertion.
C. Assertion is true but the Reason is false.
D. Both, Assertion and Reason are false.
A
B
C
D
46805.If the number of steady revolutions per minute of a conical pendulum is increased from 75 to
80, the difference in the level of bob would be
80, the difference in the level of bob would be
1.0 cm
1.5 cm
2.0 cm
2.5 cm
46806.If both the mass and radius of the earth decreases by 1%, then
the escape velocity would increase
the escape velocity would decrease
the acceleration due to gravity would increase
the acceleration due to gravity would decrease
46807.A Carnot engine, having an efficiency of $\\eta = $\\dfrac{1}{10}$ as heat engine, is used as a refrigerator. If
the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is
the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is
100 J
99 J
90 J
1 J
46808.Two thin lenses of focal lengths 20 cm and 25 cm are placed in contact. The effective
power of the combination is
power of the combination is
9D
2D
3D
7D