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പുതുവത്സരാശംസകള്‍

### Second term Exam Standard 10 -Physics (draft)

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Second Term Exam Standard 10 Physics - Answer key

1. (a) (1)
2. magenta (1)
3. (b). resistor, capacitor, diode, transistor (1)
4. decibel (dB) (1)
5. (b). The number of turns of coils in each armature is same (1)
6. a). P- Radio waves , Q – Gamma rays (1)
b). Gamma rays (1)
7. a). (d) (1)
8. I = P/V = 1500/250 = 6A (1)
H = Pxt = 1500 x 5 x 60 = 450000 J
OR
P x Hr /1000 = 1500 x (5/60 ) /1000 = .13 Unit(kWh) (1)
9. a). Earth pin should be connected to the metallic body part of the electric iron.(1)
b). Earth pin connected to the earth – If the live wires in contact with the metallic body , more current flows as it is connected to earth. This causes the breakage of fuse. (2)
10. a). 256 Hz.
b). The amplitude of the sound increases. It is due to resonance (2)
11. a). Scattering (1)
b). violet, indigo, blue (1)
c). size of the particles (1)
12. a). dark/ black (1)
b). yellow. Yellow light contains red and green.
Cyan. Cyan light contains green and blue - write any one (2)
OR
a). white (1)
b). These secondary colours are the combinations of the primary colours Red, Green and Blue. Due to persistence of vision it appears as white (2)
13. a). The electrical oscillations corresponding to the sound waves (1)
b). amplitude (1)
c). draw the graph of half wave dc (1)
14. a). Cyan (1)
b) X= green, Y= Blue (1)
c). cyan contains green and blue, it splits when the dispersion taken place. (1)
15. a). f= v/l = 340/.01m = 34000 Hz (2)
b). No. We can hear only the sound waves of frequency between 20Hz and 20000Hz.(1)
16. a). Main fuse should be connected in the phase line instead of neutral line.
Switch S2 is in earth line. It must be in the phase line (2)
b). At the place of section fuse (1)
c). It save the circuit from short-circuit, overloading, etc. It is easy to re install. (1)
17. a). The brightness of the bulb increases. When the iron core is removed, the rate of self induction decreases. (2)
b). when S1 and S2 are switched on, The bulb will not glow.
When S1 and S3 switched on, The brightness of the bulb increases.(Malayalam Med) (1)
c). The circuit becomes short-circuit and it causes the breakage of fuse. (1)

We can finalise the key after discussions........

### Second term exam Answer key - Physics standard 9

Second Term Exam-2013 Standard 9 Physics

1. Power (1)
2. The rays of light incident on the lens are parallel (1)
3. Potential Energy → Kinetic Energy → Electric Energy → Heat Energy (2)
4. A = 60W B = 2250 J (2)
5. a. Medium A (1)
b. Medium B (1)
c. It will be in straight line (1)
6. Frequency – number of vibrations per second – Hertz
Rate of change of momentum – Second law of motion – kgm/s2
action and reaction are equal and opposite – Third law of motion – rocket (3)
7. a. Force and displacement (1)
b. W= mgh = 12 x 10 x 5 = 600 J (2)
8. a. The vertical line from the centre of gravity is out side the base. (1)
b. 4 (1)
c. The point c become lower (1)
9. a. The falling due to the gravitational attraction of earth only. (1)
b. zero (1)
c. Both spheres will reach at the same time (1)
10. a. F = GMm/R2 (1)
b. F = ma (1)
c. a = GM/R2 (1)
11. a. Potential Energy (1)
b. the stone due to position and spring due to strain (1)
c. Total Energy = U = 2 x10 x 5 = 100 J (1)
It get Kinetic Energy of 100J, when just before it touches the ground (1)
12. a. A (1)
b. zero (1)
c. mass at A and B are same. Weight is more at A. (2)
13. a. because the angle of incidence is greater than critical angle. (1)
b. Total internal reflection (1)
c. Refraction is taken place here.
The angle of incidence is less than critical angle. (2)
14. (A)a. u = -6cm, v = +3cm (1)
b. yes (1)
c. 2 cm (1)
f = uv/u-v = -6 x 3 /-6 -3 = -18 / -9 = 2 cm (1)
OR
15. (B) a. Draw the Image formation (2)
b. virtual, erect, small (1)
c. Between F and O (1)

### Standard 8 - Physics - Answer key

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1. Displacement (1)
2. c. For a constant applied force the pressure increases when the surface area decreases.(1)
3. 15 cm (1)
4. a. Pascal OR N/m2 (1)
b. Vector (1)
5. a. No., The internal force doesn't move the body. (1)
b. Unbalanced External Force (1)
6. Balanced Force - b, c
Unbalanced Force – a, d (2)
7. N S N S N S
N S N S N S (1)
b. 2 (1)
1. a. Torch cells, Insulated copper wire, Nail etc. (1)
b. Wind the insulated copper wire over the nail and connect it to the battery (1)
2. a. 100 N (1)
b. 100/.25 = 400 N/ m2 (1)
c. Vertically(the area of contact will be minimum) (1)
3. a. Inertia of Motion (1)
b. The iron ball.
when the mass increases inertia increases. (2)
4. a. Magnetic Induction (1)
b. South(s) (1)
c. They will repel (1)
5. a. Gravitational Force, Buoyant Force (1)
b. They are equal and in opposite direction (1)
c. 100N (1)