PHYSICS
Electricity
Q1. The S I unit of potential difference is
(A) volt (V)
(B) ampere (A)
(C) coulomb (C)
(D) ohm meter (Ωm)
Ans: (A) volt (V)
Q2. The S I unit of electric current is
(A) ampere (A)
(B) ohm (Ω)
(C) volt (V)
(D) watt (W)
Ans: (A) ampere (A)
Q3. The rate of energy consumed in an electrical circuit is, electric
(A) current
(B) potential difference
(C) resistance
(D) power
Ans: (D) power
Q4. When three resistors of different resistance are connected in parallel in an electric circuit and switched on, then the quantity that remains the same in all the resistors is
(A) current
(B) potential difference
(C) resistance
(D) resistivity
Ans: (B) potential difference
Q5. The SI unit of resistivity is
(A) ohm-metre
(B) coulomb
(C) volt
(D) joule
Ans: (A) ohm-metre
Q6. The correct formula that shows the relationship between potential difference, electric current and resistance in an electric circuit is
(A) I = R/V
(B) I=VR
(C) V=I/R
(D) R=V/I
Ans: (D) R=V/I
Q7. A piece of metallic wire of resistance R is cut into 3 equal parts. These parts are then connected in parallel. If the total resistance of this combination is Rl, then the value of R : Rl is
(A) 1 : 3
(B) 9 : 1
(C) 1 : 9
(D) 3 : 1.
Ans: (B) 9 : 1
Q8. The resistance of a conductor is 27 Ω . If it is cut into three equal parts and connected in parallel, then its total resistance is
(A) 6 Ω
(B) 3 Ω
(C) 9 Ω
(D)27 Ω
Ans: (B) 3 Ω
Q9. SI unit of electric charge is
(A) coulomb
(B) ampere
(C) joule
(D) volt
Ans. : (A) coulomb
Q10. In an electric circuit to get an equivalent resistance Rs four resistors of 2Ω each are first connected in series. Later to get an equivalent resistance of Rp the same resistors are connected in parallel. Then the ratio of Rs/Rp is
(A) 16 : 1
(B) 2 : 1
(C) 4 : 1
(D) 8 : 1
Ans. : (A) 16 : 1
Q11. Ohm's law gives the relationship between
(A) potential difference and electric charge
(B) potential difference and resistance
(C) electric current and potential difference
(D) electric current and electric power
Ans: (C) electric current and potential difference
Q12. 0·75A current flows through an electric bulb when it is connected to a 220 V generator. Then the electric power of this bulb is
(A) 125 W
(B) 135 W
(C) 165 W
(D) 195 W
Ans. : (C) 165 W
Q13. If a device of 840W is to be used with 220V potential difference, then the rate of the fuse that is to be connected in this electrical circuit is
(A) 2A
(B) 4A
(C) 8A
(D) 12A
Ans. : (B) 4A
Q14. The resistivities of some materials at 20°C are given in the table below :
(A) N (B) K (C) M (D) L
Ans. : (C) M
Magnetic effects of electric current
1. Observe the figure given below. The magnetic field at the centre ‘C’ of circular coil is
(A) zero
(B) I
(C) 2I1
(D) 2I2
Ans: (A) zero
2. Correct statement with respect to magnetic field in the given diagram is,
(C → Current-carrying solenoid, P and Q → Points inside the solenoid,R→ Point outside the solenoid) The magnetic field
(A) in P is more than in Q
(B) in Q is more than in P
(C) in R is more than in P and in O
(D) in P and in Q is equal.
Ans: (D) in P and in Q is equal.
3. Observe the diagram.
The magnetic poles represented by P and Q respectively are
(A) south ( ) and south (S)
(B) north ( N ) and south ( S )
(C) north (N) and north (N)
(D) south (S) and north (N)
Ans. : (A) south (S) and south (S)
4. Imagine, you are holding a straight current carrying conductor as per the right hand thumb rule. If the thumb is upward, then the direction of the field lines of the magnetic field is
(A) downward
(B) upward
(C) anti-clockwise
(D) clockwise.
Ans. : (C) anti-clockwise
5. In Fleming’s left hand rule the middle finger represents the direction of
(A) magnetic fieldb
(B) current
(C) movement of conductor
(D) induced current
Ans. : (B) current
6. The magnetic field inside a long straight solenoid carrying current
(A) is the same at all points
(B) is zero
(C) decreases as we move towards its end
(D) increases as we move towards its end
Ans. : (A) is the same at all points
7. A current carrying rod is placed between the poles of a horse-shoe magnet. For the maximum displacement of the rod the angle between the direction of electric current and the direction of magnetic field must be
(A) 0°
(C) 90°
(B) 45°
(D) 180°
Ans. : (C) 90°
8. In Fleming’s left hand rule, the finger that indicates the direction of the electric current is (
(A) thumb
(B) index finger
(C) middle finger
(D) little finger
Ans. : (C) middle finger
9. If the number of turns in a current carrying circular coil is increased by 10 times, then the producing magnetic field increases by
(A) 100 times
(B) 10 times
(C) 20 times
(D) 1000 times
Ans. : (B) 10 times
LIGHT – REFLECTION AND REFRACTION
Q1. The reciprocal of focal length of lens is
(A) the power of lens
(B) the radius of curvature of lens
(C) equal to the sum of object distance and image distance
(D) equal to the difference between the object distance and image distance
Ans: (A) the power of lens
Q2. A mirror produces erect and enlarged image of an object. Then the type of mirror and the nature of that image is respectively
(A) Convex mirror and virtual image
(B) concave mirror and real image
(C) Convex mirror and real image
(D) Concave mirror and virtual image
Ans: (D) Concave mirror and virtual image
Q3. The diameter of the reflecting surface of a spherical mirror is
(A) pole of the mirror
(B) centre of curvature
(C) principal axis
(D) aperture
Ans: (D) aperture
Q4. The distance between principal focus and the optic centre of the lens is
(A) Radius of curvature
(B) Object distance
(C) Focal length
(D) Image distance
Ans: (C) Focal length
Q5. The correct statement among the following related to the concave lens is
(A) converges the light rays
(B) diverges the light rays
(C) forms inverted image
(D) forms real image.
Ans. : (B) diverges the light rays
Q6. To get diminished and real image of an object from a convex lens, the object should be placed
(A) at principal focus F1
(B) between principal focus F1 and 2F1
(C) beyond 2F1
(D) between principal focus F1 and optical centre O.
Ans. : (C) beyond 2F1
Q7. An object is kept at the centre of curvature of a concave mirror. The position and nature of the image formed is
(A) between F and C and inverted
(B) behind the mirror and erect
(C) between F and P and erect
(D) at the centre of curvature and inverted
Ans. : (D) at the centre of curvature and inverted.
Q8. To obtain a diminished image of an object from a concave mirror, position of the object should be (F = principal focus, C = centre of curvature, P = pole)
(A) between C and F
(B) beyond C
(C) between P and F
(D) at F
Ans. : (B) beyond C
Q9. Identify the emergent ray in the given figure.
A) CD
(B) BC
(C) AB
(D) IJ
Ans. : (A) CD
Q10. Type of the mirror used in vehicles as rear view mirror is
(A) plane mirror
(B) concave mirror
(C) convex mirror
(D) planoconcave mirror
Ans. : (C) convex mirror.
Q11. To get virtual and erect image by a convex lens, an object is to be placed
(A) beyond 2F1
(B) between F1 and 2F1 ]
(C) at focus F1
(D) between focus F1 and optical centre O
Ans. : (D) between focus F1 and optical centre O.
Q12. Convex mirrors are used in
(A) torches
(B) rear view mirrors in vehicles
(C) search-lights
(D) shaving mirrors
Ans. : (B) rear view mirrors of vehicles
Q13. The power of a lens is + 2D. Then the focal length of that lens is
(A) 0·5 m (B) 2 m (C) 0·2 m (D) 5 m
Ans. : (A) 0·5 m
Q14. If a ray of light enters from denser medium to a rarer medium obliquely, then the correct statement related to the speed and bending of that light ray in the rarer medium is
(A) speed decreases and bends towards the normal
(B) speed increases and bends away from the normal
(C) speed decreases and bends away from the normal
(D) speed increases and bends towards the normal
Ans. : (B) speed increases and bends away from the normal
Human Eye and Colorful World
Q1. The sky as seen from the surface of the moon appears dark because
(A) only a little of the blue and violet colours are scattered
(B) all the colours are absorbed by the atmosphere present in the moon
(C) all the colours are scattered Total
(D) atmospheric particles needed to scatter the light are not present.
Ans. : (D) atmospheric particles needed to scatter the light are not present.
Q2. Right statement regarding the colour of the scattered sunlight and the size of scattering atmospheric particles is
(A) small particles scatter red colour
(B) big particles scatter blue colour
(C) big particles scatter violet colour
(D) too larger particles scatter all colours equally
Ans. : (D) too larger particles scatter all colours equally
Q3. The colour that is least scattered by fog and smoke is
(A) orange
(B) blue
(C) red
(D) violet
Ans. : (C) red
Q4. Identify the wrong statement among the following statements regarding refraction and dispersion of light.
(A) Stars twinkle
(B) Sky appears blue to an astronaut flying at very high altitudes
(C) The sun is visible to us about two minutes before the actual sunrise
(D) Planets do not twinkle
Ans. : (B) Sky appears blue to an astronaut flying at very high altitudes
Q5. The crystalline lens of the eye in old age people sometimes becomes milky and cloudy. This condition is called
(A) Hypermetropia
(B) Myopia
(C) Presbyopia
(D) Cataract
Ans: (D) Cataract
Q6. The sun is visible to us about two minutes before the actual sunrise and about two minutes even after the actual sunset because of atmospheric
(A) refraction of light Total
(B) reflection of light
(C) scattering of light
(D) dispersion of light
Ans. : (A) refraction of light
Q7. Observe the diagrams given below :
The correct conclusion that you can draw here is that, the angle of deviation will be
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