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SECTION - A
1. What does the term ohmic heating indicates?
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(C) Joule heating |
| 2. Statement: If the stem of a tuning fork is placed on a table, the sound heard increases.
Reason: if the frequency of the forcing object and the natural frequency of the forced object are not equal, the objects are said to be in resonance.the frequency of the object undergoing resonance will increase.
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(C) Statement is correct, reason is incorrect |
| 3. When passing through water droplets when forming rainbow light rays undergo: |
(C) (i), (ii), and (iv) correct |
| 4. Match the following |
(C) ABF and DEC |
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SECTION - B
5. A boy is standing between two buildings. If he shouts he hears the echo from the first building in 0.2 seconds and the echo from the second building in 0.3 seconds. (speed of sound in air = 340 m/s).
(i) What is the condition to produce an echo?
(ii) Calculate the distance between two buildings
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(i) The minimum distance between the source of sound and the reflecting surface must be 17 meters (so that the reflected sound reaches the ear after an interval of at least 0.1 seconds).
(ii) 85 meters
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7 (ii) In winter, path of light through the gaps of the branches of trees can be seen clearly due to scattering.
(a) By what name is the phenomenon known where the path of light becomes visible in this manner? Through what type of medium does light travel when this occurs?
(b)What does the intensity of scattering depend
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(a) Name - Tynadall Effect , Medium - Colloidal Medium
(b) Intensity depends on - The size of scattering particles and wavelength of light
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8. A portion of electric circuit diagram of a household wiring is given:
(a) What does the part marked at ‘X’ present in the circuit.
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(a) Main switch (double pole switch)
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9. A load of 20000 N is lifted with a wheel and axle system that has a wheel of radius 50 cm and an axle of radius 10 cm.
(a) Calculate the mechanical advantage of this wheel and axle.
(b) How should a wheel and axle be designed to obtain increased mechanical advantage
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(a) 5
(b) Increase the weel radius or decrease the axle radius
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10. (A) A heating appliance produces 7200000J Reat in 2 hours.
(a) What is the energy change in a heating appliance?
(b) Calculate the power of this appliance
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(a) Electrical energy to heat energy
(b) 1000 W
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10 (B) An electric grinder with a power of 400 W is working.
(a) What is the energy change in this equipment ?
(b) Calculate the work done by this grinder in 1 minute.
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(a) Electrical energy to Mechanical energy
(b) Work done - 4000J
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11. Observe the figure showing a rule related to electricity and magnetism. Which law does this figure represent? State the rule
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Right Hand Thumb Rule
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12. Observe the figure where three coloured lights are made to fall on a screen.
(a) Which colours are labelled as A and D?
(b) Among the colours A, B, C and D identity the primary colours and write down the colours.
(c) There is a complementary colour pair among A, B, C and D. Pick them out and write down.
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(a) A : Green ; D: Yellow
(b) Primary colours: Red, Green (A), Blue (B)
(c) Complementary pair: Blue (B) Yellow (D)
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13. The resistance of a heating coil in a heating appliance operating at 200 V is 60 Ω
(a) Which alloy is used to make heating coil of heating appliances?
(b) Calculate the amount of heat produced if electricity flows through this appliance for 5 minutes.
(c) If another appliance with a resistance less than 60 Ω is operated at the same voltage for 5 minutes, will the amount of heat produced increase or decrease ? What is your justification
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(a) Nichrome
(b) 200,000 J
(c) Effect: Heat will increase ; Justification: At constant voltage heat is inversely proportional to resistance
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14. A. Observe the figure and answer the questions:
(a) Which one has the mechanical advantage less than one ?
(b) State the principle of a lever.
(c) The mechanical advantage of a lever is 2. If the length of its effort arm is 1 m, calculate the length of the load arm.
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(a) MA less than one - Figure iii
(b) Load x Load Arm = Effect x Effet Arm
(c) 0.5m
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14. B. Crowbar can be used as a lever.
(a) What do you mean by a lever ?
(b) Among Effort, Load, and Fulcrum, state which one comes in the middle for a second order lever and for a third order lever.
(C.) A metre scale is suspended in an equilibrium position. If a weight of 60 g wt is suspended at a distance of 25 cm from the balanced point, what weight must be suspended on the other side at a distance of 30 cm to keep the metre scale in equilibrium ?
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(a) A rigid bar capable of turning about a fixed point.
(b) 2nd order = Load, 3rd order = effort
(c) 50g W
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15. Observe the figure and answer the questions:
What is meant by a solenoid ?
(a) The end connected to the positive terminal of the cell will always be the North pole of a solenoid. Is this statement correct? Justify your answer. :
(b) Write any two ways to increase the strength of the magnetic field formed around a current carrying solenoid.
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(a) an insulated copper wire wound in a helical shape
(b) Polarity depends on the directtion of current flow.
(c) Increase the number of turns or increase current intensity
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16. Observe the figure and answer the questions:
(a) Which type of mechanical wave is this ?
(b) What do the letters C and R indicate ?
(C.) If the distance between two consecutive 'C' of the wave is 0.01 m, which is travelling with a speed of 350 m/s, will it be audible to humans? Justify your answer by mathematical calculation.
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(a) Longitudinal wave
(b) C: Compression ; R: Refraction
(c) 35,000 Hz, No
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17. A. An object is placed 20 cm away from a concave lens with a focal length of 10 cm.
(a) Calculate the distance to the image from the lens.
(b) Write down the characteristics of the image.
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(a) 6.67 cm
(b) Virtual, errect, and diminished
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17. B. A convex lens forms a virtual image at a distance of 7.5 cm away from it. Focal length of the lens is 15 cm.
(a) Calculate the distance between lens and the object.
(b) Write any two instances where a convex lens is used in this manner.
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(a) -5 cm
(b) Magnifyin glass or eyepiece of a microscope
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