Class 7 half yearly exam 2022-23

 Sub- physics

Class-7

M.M: 80

Time: 2hrs

Section-A(50 marks)

Answer all questions.

Q1 fill in the blanks: (10)

1.1 the image formed by a plane mirror is at a distance behind the mirror as........

1.2 we are able to see objects around us due to........ Reflection.

1.3 a ...... Image cannot be obtained on screen.

1.4 a plane mirror......... Reflects 100% light falling on it.

1.5 blue, Red and green are the........ Colours.

1.6 on heating a body, it's temperature.........

1.7 the SI unit of temperature is........

1.8 the temperature of a normal human body is....... °C.

1.9 heat transfer in solids is by........

1.10 black and Dull surfaces are........ Of heat.

Q2. Write true or false for each statement: (10)

(10)

2.12.1 all solids expand by the same amount when heated to the same rising temperature.

2.2 water is bad conductor of heat.

2.3 kerosene contracts on heating.

2.4 black surfaces are poor absorbers of heat radiations.

2.5 medium is necessary for the transfer of heat radiation.

2.6 the image formed by a plane mirror is upright.

2.7 the image formed by a plane mirror can be obtained on a screen.

2.8 a rose  appears red in light of all the colours.

2.9 the speed of light in vacuum is 3× 10⁶ ms-¹.

2.10 the image formed by plane mirror is lateral inverted.

Q3. Match the following: (10)

3.1 light ray passes from air to glass.     A. Speed up

3.2 virtual image.                               B. Reflects red light.

3.3 A light ray passes from glass to water  C. plane                                                                                         mirror

3.4 red rose.            D. Secondary colours

3.5 magenta, yellow & cyan    E. slows down

3.6 Mercury.            F. Insulator

3.7 wood.              G. Water from 0°C to 4°C.

3.8 aluminium.   H. Absorbs

3.9 contracts.        I. Conductor

3.10 black surface.   J. Thermometer

Q4. Answer the following questions: (2×10=20)

4.1 what is heat? State its SI unit.

4.2 name the two scales of temperature. How are they interrelated?

4.3 why do telephone wires sag in summer? Explain.

4.4 what are good and bad conductors of heat? Give examples of each.

4.5 what are land and sea Breezes?

4.6 state the laws of reflection of light.

4.7 state two uses of a plane mirror.

4.8 write down the letter C & D as seen in a plane mirror.

4.9 the leaves appears green in white light. How will it appear in green and red light?

4.10 convert - 40°C to the °F scale.

Section-B(30 marks)

Answer any three questions:

Q5.1 draw a ray diagram showing the formation of image of a point object by a plane mirror. 

5.2 write four differences between real and virtual image. (6+4=10)

Q6.1 state any four characteristics of the image formed by a plane mirror. (4)

6.2 fill in the blanks with appropriate colour: (3)

A. Blue + ......... = Cyan

B. ........, + ......     = Magenta

C. ........ +  Blue    = white.

6.3 state the speed of light in  (3)

A.air

B. Glass

C. Water

Q7.1 draw a neat labelled diagram of a thermos flask. How the transfer of heat by conduction , convection and radiation is reduced? (6)

7.2 name the mode of transfer of heat in the following: (4)

A. Liquid

B. Vacuum

C. Gas

D. Solid

Q8.1 describe an experiment to show that liquids expand on heating.  (3+1+2+4=10)

8.2 define temperature.

8.3 draw a neat level diagram of a laboratory thermometer.

8.4 the temperature of a body Rises by 1°C. What is the corresponding rise on the:

A. Fahrenheit scale

B. Kelvin scale?