# IIT JEEE Physics - 1982

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### IIT JEE –Past papers:

IIT JEE –Past papers PHYSICS- UNSOLVED PAPER - 1982

### SECTION – I:

SECTION – I Single Correct Answer Type This section contains 10 multiple choice questions. Each question has four choices (A), (B), (C) and (D) out of which ONLY ONE is correct.

### Problem:

01 In the arrangement as shown in the figure below, the ends P and Q of an inextensible string move downwards with uniform speed u. Pulleys A and B are fixed. Mass M moves upwards with a speed. a. 2u cos θ b. u/ cos θ c. 2u/ cos θ d. ucos θ Problem

### Problem:

Problem 02 A particle is moving eastwards with a velocity 5 m/s. In 10 seconds the velocity changes to 5 m/s northwards. The average acceleration in this time is a. Zero b. towards north-west c. towards north –west d. towards north

### Problem:

Problem 03 A body floats in a liquid contained in a beaker. The whole system as shown in the figure falls freely under gravity. The up thrust on the body due to the liquid is heard by the car driver is a. Zero b. Equal to the weight of the liquid displaced c. Equal to the weight of the body in air d. Equal to the weight of the immersed portion of the body

### Problem:

Problem 04 Two particles initially at rest move toward each other under a mutual force of attraction. At the instant when the speed of A is V and the speed of B is 2 V, then the speed at the centre of the mass of the system is a. Zero b. 1.5 V c. V d. 3 V

### Problem:

Problem 05 In Young’s double slit experiment the interference pattern is found to have an intensity ratio between bright and dark fringes as 9. This implies that a. The intensities at the screen due to the two slits are 5 units and 4 units respectively. b. The intensities at the screen due to the slits are 4 units and 1 unit respectively. c. The amplitude ratio is three. d. The amplitude ratio is two.

### Problem:

Problem 06 A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is a. -1 .5 D b. -0.5 D c. 6 .5 D d. 6. 67 D

### Problem:

Problem 07 A wave equation which gives the displacement along y direction is given by where x and y are in meters and t is time in seconds. This represents a wave a. Traveling with a velocity of 30m/s in the negative x direction b. Of wave length meters. c. Of frequency 30/ Hertz. d. Of amplitude 10 -4 m traveling along the negative x direction

### Problem:

Problem 08 A magnetic needle is kept in a non-uniform magnetic field. It experiences a. A force and a torque b. A force but not a torque. c. A torque but not a force d. Neither a force nor a torque

### Problem:

Problem 09 The shortest wavelength of x-rays emitted from an X-ray tube depends on a. The current in the tube b. The voltage applied to the tube. c. The nature of the gas in the tube d. The atomic number of the target material

### Problem:

Problem 10 The threshold wavelength for photoelectric emission from a material is 5200Å Photoelectrons will be emitted when this material is illuminated with monochromatic radiation from a a. 50 watt red lamp b. 1 watt neon lamp c. 50 watt infrared lamp d. 1 watt ultraviolet lamp

### SECTION – II:

SECTION – II Each of which either True or False This question contains five statements, each of which is either true of false. Indicate your choice of the answer in the answer-book by writing TRUE or FALSE for each statement.

### Problem :

Problem 11 State whether the questions are true or false i . The volume V versus temperature T graphs for a certain amount of a perfect gas at two pressures are as shown in the figure. It follows from the graph that ii. Two different gases at the same temperatures have equal root mean square velocities. iii. Electrons in a conductor have no motion in absence of a potential difference across it.

### Slide 15:

FOR SOLUTION VISIT WWW.VASISTA.NET 