1 Electronic Devices
Ge at absolute temp is a :
(1) super condutor (2) conductor (3) semi conductor (4) insulator
2 Dual Nature of Matter and Radiation
A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then
1) each emitted electron carries one quarter of the initial energy 2) number of electrons emitted is half the initial number 3) each emitted electron carries half the initial energy 4) number of electrons emitted is a quarter of the initial number
photoelectric current $$I\infty$$ intensity of light and$$Intensity \infty \, \dfrac{1}{(distance)^{2}}$$ $$\therefore \, I \, \infty \, \dfrac{1}{(distance)^{2}}$$
3
Block of mass 4 kg rests on a rough inclined plane making an angle of 30 with the horizontal. The coefficient of static friction between the block and the plane is 0.7. The friction force on the block is: 1. 9.8 N2. 13.5 N3. 16.8 N4.19.6 N
4 Properties of Bulk Matter
The hydrostatic pressure on the dam wall at the bottom of a deep reservoir depends upon the (1) Depth of the water (2) Surface area of the water (3) Length of the reservoir (4) Thickness of the wall
5 Electronic Devices
The n-type semi-conductor is:
(1) Germanium doped with aluminum (2) Silicon doped with indium. (3) Germanium doped with arsenic (4) Germanium doped with indium.
6 Physical world and measurement
Dimensional formula of Stefan-Boltzmann's constant is ... . Take dimension of temperature as J 1) M1L2T-1K4 2) M1L0T-3K-4 3) M1L2T-2K4 4) M1L2T-3K4
Solution
Stefan-Boltzmann constant = Power/ Area ×(temperature)4
7 Current Electricity
A 240-Volt appliance draws 15A of current for a period of 2 hours. How much energy in kilowatt-hours does it consume?
1) 7.2
2) 2 .6 x107
3) 7200
4) 3600
8 Kinematics
A bus moving on a level road with a velocity $$V$$ can be stopped at a distance of $$x$$, by the application of a retarding force $$F$$. The load on the bus is increased by $$25\%$$ by boarding the passengers. Now, if the bus is moving with the same speed and if the same retarding force is applied, the distance travelled by the bus before it stops is:
1) x 2) 1.25x 3) 5x 4) 2.5x
9 Oscillations
A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 ms-1 at an angle of 60° with the source observer line as shown in the figure. The observer is at rest. The apparent frequency observed by the observer (velocity of sound in air 330 ms-1)is :- 1) 97 Hz 2) 100 Hz 3) 103 Hz 4) 106 Hz
Component of Vs along observer = Vscosθ =19.4 × cos60 =9.7 Using formula for source moving to wards observer at rest
10 Motion of System of Particles and Rigid Body
A reference frame attached to the Earth 1) is an inertial frame by definition. 2) is an inertial frame because Newton's laws of motion are applicable inside it. 3) is not an inertial frame because the Earth moves with respect to the Sun. 4) cannot be an inertial frame of reference because of the Earth's rotation and revolution.
An inertial frame of reference is one which has a constant velocity and no acceleration. Because of the Earth's rotation and revolution, the direction of motion keeps changing and therefore the velocity is not constant. Hence this is not an inertial frame of reference.
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