Dakshana Mock Test Season XII

Dakshana Mock Test Season XII

1] A metallic conductor carries 800mA current from left to right. It means that

i. 5*10¹⁸ protons are flowing per second from left to right
ii. 5*10¹⁸ electrons are flowing per second from right to left
iii. 8*10² electrons are flowing per second from right to left
iv. 5*10¹⁸ protons are flowing per second from left to right & 5*10¹⁸ electrons are flowing per second from right to left

2] Ohm's law (I = V/R) is applicable for

i. All types of conductors of electricity
ii. Only metallic conductors of electricity
iii. Only semi conductors of electricity
iv. Only from metallic and ionic conductors of electricity

3] A copper wire has a resistance of 8 ohm. The wire is stretched to double of its original length. Its new resistance will be

i. 8 ohm
ii. 16 ohm
iii. 32 ohm
iv. 64 ohm

4] A beam of light traveling in air enters into a liquid. Its speed reduces by 30%. The refractive index of liquid with respect to air is

i. 10/7
ii. 10/3
iii. 7/5
iv. 4/3

5] The refractive index of a liquid is 5/3. A ray of light traveling in this liquid falls at interface of liquid and air. At what angle of incidence should it fall on liquid air interface so that, it suffers total internal reflection?

i. 53°
ii. 24°
iii. 15°
iv. 17°

6] A beam of light in air is incident upon the smooth plane surface of a piece of flint glass making an angle of 30° with its plane. If the reflected beam and refracted beam are perpendicular to each other, what is the index of refraction of flint glass with respect to air?

i. 1/2
ii. √3/2
iii. 2/√3
iv. √3

7] The image created by a converging lens is projected on a screen that is 60 cm away from the lens. If the height of the image is one fourth the height of the object, what is focal length of the lens?

i. 36cm
ii. 45cm
iii. 80cm
iv. 48cm

8] An electric bulb is marked (60 W, 120 V). What is the resistance of filament of bulb?

i. 2Ω
ii. 30Ω
iii. 240Ω
iv. 720Ω

9] A battery whose emf is 40 V has an internal resistance 5Ω. If, this battery is connected across a 15Ω resistor (R), what will be voltage drop across resistor (R) ?

i. 10 V
ii. 30 V
iii. 40 V
iv. 50 V

10] Three identical bulbs B₁, B₂ and B₃ are connected in parallel across terminals of an ideal source of emf. What will happen if bulb B₂ burns out?

i. Bulb B₁ and B₃ will also burn out
ii. Bulb B₁ and B₃ will give less light
iii. Bulb B₁ and B₃ will give more light
iv. Bulb B₁ and B₃ will give same light

11] A bar magnet is cut into two equal parts by cutting it very slowly perpendicular to its length. Which of the following is true?

i. Each part will be a bar magnet having two equal and opposite poles same as original magnet
ii. One part will have a N-Pole and other part will have a S-Pole of same strength as original magnet
iii. Each part will be a bar magnet having two equal and opposite poles of strength half of original magnet
iv. None of two parts will be a magnet

12] Which of the following cannot form a real image for a divergent beam of light?

i. Plane mirror only
ii. Convex mirror only
iii. Concave lens only
iv. All of the above

13] Three resistors of resistance Ω/60, Ω/30 and Ω/20 are joined in parallel. The equivalent resistance of combination will be

i. Ω/110
ii. Ω/10
iii. 110Ω
iv. 10Ω

14] A rod of length 5cm lies along the principal axis of the concave mirror of focal length 15cm in such a way that the end of the closer to the pole is 30cm away from it. Then, the length of the image is

i. 2.75cm
ii. 3.75cm
iii. 4.75cm
iv. None of the above

15] If an object moves towards or away a plane mirror with a velocity 'v' then the image will approach or recede with velocity

i. v
ii. 2v
iii. 3v
iv. 4v

16] The focal length of a concave mirror depends upon the

i. Distance of the object from the mirror
ii. Distance of the image from the mirror
iii. Radius of curvature of the mirror
iv. None of these

17] The rainbow is formed due to ___.

i. Refraction
ii. Internal reflection
iii. Dispersion
iv. All of the above

18] A person cannot see distinctly any object placed beyond 40cm from his eye. What is the power of the lens which will enable him to see distant stars clearly?

i. +2.5D
ii. -2.5D
iii. +3.5D
iv. -3.5D

19] An electrical power station has the power 200 Megawatt (MW), then the electrical energy produced per day will be

i. 200 MWh
ii. 4800 MWh
iii. 4800 MW
iv. 4800 joule

20] How many electrons flow per second through the filament of 220V and 110W electric bulb?

i. 3.125 * 10¹⁸
ii. 3.125 * 10¹⁹
iii. 4.125 * 10¹⁹
iv. 4.125 * 10¹⁸

21] The S.I. unit of electrical resistivity is

i. ohm
ii. m
iii. ohm * m^-1
iv. ohm * m

22] A bulb of 100 Watt, 250 Volt has the resistance of

i. 2500 ohm
ii. 625 ohm
iii. 25 ohm
iv. 2.5 ohm

23] A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R₁, then the ratio R / R₁ is

i. 1/25
ii. 1/5
iii. 5
iv. 25

24] Magnetic effect of current were discovered by

i. Faraday
ii. Oersted
iii. Joule
iv. Ampere

25] An electron enters a magnetic field at right angles to it as shown in figure. The direction of force acting on electron will be

i. To the right
ii. To the left
iii. Out of the page
iv. Into the page

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