23241.If n denotes a positive integer, h the Planck’s constant, q the charge and B the magnetic field, then the quantity $\dfrac{nh}{2\pi qB}$ has the dimension of
area
length
speed
acceleration
23260.A Vernier calipers has 1 mm marks on the main scale. It has 20 equal divisions on the Vernier scale which match with 16 main scale divisions. For this Vernier calipers, the least count is
0.02 mm
0.05 mm
0.1 mm
0.2 mm
23276.An ideal gas heat engine operates in a Carnot cycle between 227ºC and 127ºC. It absorbs 6 kcal at the higher temperature. The amount of heat (in kcal) converted into work is equal to
4.8
3.5
1.6
1.2
23280.A body of mass 100 gram, tied at the end of a string of length 3 m rotates in a vertical circle and is just able to complete the circle. If the tension in the string at its lowest point is 3.7 N, then its angular velocity will be ______ (g = 10 m/s2)
4 rad/s
3 rad/s
2 rad/s
1 rad/s
23293.A car is moving with a speed of 30 m/s on a circular path of radius 500 m. Its speed is increasing at the rate of 2 m/s2. The acceleration of the car is
9.8 m/s2
1.8 m/2
2 m/s2
2.7 m/s2
23302.A cyclist goes round a circular path of circumference 343 m in $\sqrt{22}$s. The angle made by him, with the vertical is
42°
43°
44°
45°
23307.A cyclist turns around a curve at 15 miles per hour. If he turns at double the speed, the tendency of overturn is
doubled
quadrupled
halved
unchanged
23321.A particle of mass m is moving in a horizontal circle of radius R with uniform speed v. When it moves from one point to a diametrically opposite point its
kinetic energy changes by Mv2/4
momentum does not change
momentum changes by 2 Mv2
kinetic energy changes by Mv2
23335.A stone of mass 250 gram, attached at the end of a string of length 1.25 m is whirled in a horizontal circle at a speed of 5 m/s. What is the tension in the string?
2.5 N
5 N
6 N
8 N
23337.A tube of length L is filled completely with an incompressible liquid of mass M and closed at both the ends. The tube is then rotated in a horizontal plane about one of its ends with a uniform angular velocity ω. The force exerted by the liquid at the outer end is
$\dfrac{ML\omega^2}{2}$
MLω2
$\dfrac{ML^2\omega^2}{2}$
$\dfrac{ML\omega^2}{4}$
23379.Maximum acceleration of the train in which a 50 kg box lying on its floor will remain Stationery
(Given : Co–efficient of static friction between the box and the train’s floor is 0.3 and g = 10 ms–2)
(Given : Co–efficient of static friction between the box and the train’s floor is 0.3 and g = 10 ms–2)
5.0 ms–2
3.0 ms–2
1.5 ms–2
15 ms–2
23398.A block of mass 10 kg moving in $x$ direction with a constant speed of 10 ms–1, is subjected to a retarding force F = 0.1$x$ J/m during its travel from $x$ = 20 m to 30 m. Its final KE will be
475 J
450 J
275 J
250 J
23401.Statement–1 : Two particles moving in the same direction do not lose all their energy in a completely inelastic collision.
Statement–2 : Principle of conservation of momentum holds true for all kinds of collisions.
Statement–2 : Principle of conservation of momentum holds true for all kinds of collisions.
Statement–1 is true, Statement–2 is false
Statement–1 is true, Statement–2 is true; Statement–2 is the correct explanation of Statement–1
Statement–1 is true, Statement–2 is true; Statement–2 is the not the correct explanation of Statement–1
Statement–1 is false, Statement–2 is true
23410.A particle of mass m is driven by a machine that delivers a constant power k watts. If the particle starts from rest the force on the particle at time t is
$\sqrt{\dfrac{mk}{2}} t^{–\dfrac{1}{2}}$
$\sqrt{mk} t^{–\dfrac{1}{2}}$
$\sqrt{2mk} t^{–\dfrac{1}{2}}$
$\dfrac{1}{2}\sqrt{mk} t^{–\dfrac{1}{2}}$
23422.The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately:
540 nm
400 nm
310 nm
220 nm
23423.According to Einstein s photoelectric equation, the plot of the kinetic energy of the emitted photoelectrons from a metal Vs the frequency, of the incident radiation gives a straight line whose slope:
depends on the nature of the metal used
depends on the intensity of the radiation
depends both on the intensity of the radiation and the metal used
is the same for all metals and independent of the intensity of the radiation
23424.Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6 eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is
+3 V
+4 V
–1 V
–3 V
23425.If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de–Broglie wavelength of the particle is
25
75
60
50
23448.The following figure shows a logic gate circuit with two inputs A and B and the output C. The voltage waveforms of A, B and C are as shown below
The logic circuit gate is:
The logic circuit gate is:
AND gate
NAND gate
NOR gate
OR gate
23450.Two charges, each equal to q, are kept at x = – a and x = a on the x–axis. A particle of mass m and charge q0 = q/2 is placed at the origin. If charge q0 is given a small displacement (y << a) along the y–axis, the net force acting on the particle is proportional to
y
–y
$\dfrac{1}{y}$
–$\dfrac{1}{y}$
23469.If a wire is stretched to make it 0.1% longer, its resistance will
increase by 0.05%
increase by 0.2%
decrease by 0.2%
decrease by 0.05%
23475.Shown in the figure below is a meter–bridge set up with null deflection in the galvanometer.
The value of the unknown resistor R is
The value of the unknown resistor R is
220 Ω
110 Ω
55 Ω
13.75 Ω
23491.A 5V battery with internal resistance 2 Ω and a 2V battery with internal resistance 1 Ω are connected to a 10 Ω resistor as shown in the figure.
The current in the 10 Ω resistor is
The current in the 10 Ω resistor is
0.03 A P1 to P2
0.03 A P2 to P1
0.27 A P1 to P2
0.27 A P2 to P1
23496.A circuit contains an ammeter, a battery of 30 V and a resistance 40.8 ohm all connected in series. If the ammeter has a coil of resistance 480 ohm and a shunt of 20 ohm, the reading in the ammeter will be
1 A
0.5 A
0.25 A
2 A
23497.A material ‘B’ has twice the specific resistance of ‘A’. A circular wire made of ‘B’ has twice the diameter of a wire made of ‘A’. Then for the two wires to have the same resistance, the ratio $l$A / $l$B of their respective lengths must be
1
2
1/2
1/4
23507.A proton beam enters a magnetic field of 10–4 Wb m–2 normally. If the specific charge of the proton is 1011 C kg–1 and its velocity is 10° ms–1, then the radius of the circle described will be
100 m
0.1 m
1 m
10 m
23525.The magnetic lines of force inside a bar magnet
are from north–pole to south–pole of the magnet.
do not exist.
depend upon the area of cross–section of the bar magnet.
are from south–pole to north–pole of the magnet.
23536.At a specific instant, emission of radioactive compound is deflected in a magnetic field. The compound can emit
(i) electrons
(ii) protons
(iii) He2+
(iv) neutrons
The emission at instant can be
(i) electrons
(ii) protons
(iii) He2+
(iv) neutrons
The emission at instant can be
i, ii, iii
i, ii, iii, iv
iv
ii, iii
23539.A radar has a power of 1 kW and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance up to which it can detect object located on the surface of the earth(Radius of earth = 6.4 × 106 m) is :
80 km
16 km
40 km
64 km
23540.The electric and magnetic field of an electromagnetic wave are
in opposite phase and perpendicular to each other
in opposite phase and parallel to each other
in phase and perpendicular to each other
in phase and parallel to each other.