Class – X Sub: - Physics F.M -100
Section – A
Choose the correct alternative ( MCQ) 1 x 25 = 25
Q 1. What is the SI unit of power of a lens ? a) Watt b) Diopter c) Lumen d) Meter
Q2 ,Which material is non- magnetic ? a) Iron b) Nickel c) Copper d) Cobalt
Q3. The resistance of a wire of length L and cross-sectional area is R . What is the new resistance if length is doubled and area is halved ? a) R/2 b) 2R c) 4R d) R/4
Q4 . The change in the direction of a wave passing from one medium to another is termed as ---------- a) Interference b) Mirage c) Diffraction d) Refraction
Q5 what would be the angle of incidence for a light ray having zero reflection angle ? A) 180 degree b) 90 degree c) 0 degree d) 45 degree
Q6. A full length of the image of a distant tall building can be seen using ----------- a) a convex mirror b) a plane mirror c) a concave mirror d) none of the options
Q7 . The ratio of the sine of the angle of incidence to the the sine of the angle of refraction is constant . It is given by --------- a) Faraday’s law b) Snell’s law c) Newton’s law d) Murphy’s law
Q8 . Electrical resistivity of a metallic wire depends upon its -------a) Length b) Material c) Thickness d) Shape
Q9 . Electrical current is measured using ----------- a) Galvanometer b) Ammeter c) Voltmeter d) Potentiometer
Q10 . Materials which do not allow electricity to pass through are known as ---------- a) Semiconductor b) Conductor c) Insulator d) Semi-insulator
Q11. Copper is used in electric transmission lines because it has ----------- a) High resistivity b) Low resistivity c) No resistivity d) None of the option
Q12 . Magnetic field lines emerge from a) South pole b) North pole c) Centre of magnet d) None of the option
Q13 . Magnetic field is a a) Scalar quantity b) Vector quantity c) Dimensionless quantity d) None of the option
Q14. Which of the following is used to detect the presence of current in a circuit ? a) Meter bridge b) Sonometer c) Galvanometer d) Electric motor
Q15. The force exerted on a current carrying wire placed in a magnetic field is zero when the angle between the wire and the direction of the magnetic field is -------- a) 180 m degree b) 45 degree c) 90 degree d) 60 degree
Q16. Unit of electric power may also be expressed as a) Watt second b) Ampere hour c) Volt ampere d) Kilowatt hour
Q17 . How does the eye change in order to focus on near or far objects ? a) The lens moves in or out b) The pupil gets smaller c) The retina moves in or out d) The lens becomes thicker or thinner
Q18. The crystalline lens of people at bold age becomes milky and cloudy , this condition is known as -------- a) Hypermetropia b) Myopia c) Cataract d) Presbyopia
Q19 . In the rearview mirror of the vehicle what will be the magnification ? a) 1 b) greater than 1 c) less than 1 d) No magnification seen
Q20 . In which of the following does light travel fastest ? a) Oil b) Water c) Air d) Paper
Q21 . Electric potential is a ---------------- a) Vector quantity b) Scalar quantity c) Dimensionless quantity d) None of the above
Q22 . Which of the following is the good conductor of electricity ? a) Paper b) Iron c) Glass d) Ebonite
Q23. Concave lens produces ----------- a) only virtual image b) only erect image c) only diminished image d) virtual erect and diminished image
Q24. The laws of reflection are valid for ----------- a) a convex mirror b) a plane miror c) a concave mirror d) all mirrors irrespective of their shapes
Q25. Twinkling of stars is due to which optical phenomenon ? a) Reflection b) Interference c) Refraction d) Divergence
Section –B
Answer the following question with few words ; 2 x 6 = 12
Q26. A pencil when dipped in water in aglass tumbler appears to be bent at the interface of air and water . Why ?
Q27. How is the refractive index of a medium related to the speed of light ?
Q28. Refractive index of diamond with respect to glass is 1.6 and absolute refractive index of glass is 1.5 . Find the absolute refractive index of diamond ?
Q29. Should the resistance of an ammeter be low or high ? Give reason .
Q30 .How does use of a fuse wire protect electrical appliances ?
Q32. Why is parallel arrangement used in domestic wiring ?
Section – C
Answer the following questions : 3 x 6 = 18
Q 33 . State Ohm’s law ? Does it hold good under all conditions ?
Q34. What is Joule’s heating effect ? Stae the related laws .
Q35 . What does the direction of thumb indicate in the right hand thumb rule . In what way this rule is different from Fleming’s left hand rule ?
Q36. What is the difference between a direct current and an alternating current ? How many times does AC used in India change direction in one second ?
Q37 .Explain the phenomenon of dispersion of white light through a glass prism , use suitable ray diagram .
Q38 . How are power and focal length of a lens related ? You are provided with two lenses of focal length 20 cm. And 40 cm respectively . Which lens you use to obtain more convergent rays ?
Section – D
The following questions from Q 39 to Q 43 are Assertion (A) , and Reason(R) type question . You have to choose one of the four alternative as correct answer . 1x 5 = 5
a) Both A and R are true R is the correct explanation of A
b) Both A and R are true but R is not the correct explanation of A
c) A is true but R is false
d) A is false but R is true
Q39 . Assertion (A) : A ray passing through the centre of curvature of a concave mirror after reflection, is reflected back along the same path.
Reason (R) : The incident rays fall on the mirror along the normal to the reflecting surface.
Q40 . Assertion(A) : The emergent ray is parallel to the direction of the incident ray.
Reason (R) : The extent of bending of the ray of light at the opposite parallel faces (air- glass interface and glass-air interface) of the rectangular glass slab is equal and opposite.
Q41. Assertion (A) : If a graph is plotted between the potential difference and the current flowing, the graph is a straight line passing through the origin.
Reason (R) : The current is directly proportional to the potential difference.
Q42. Assertion (A) : Longer wires have greater resistance and the smaller wires have lesser resistance.
Reason (R) : Resistance is inversely proportional to the length of the wire.
Q43. Assertion(A): The magnitude of the magnetic field at a point on the axis of a current carrying solenoid is inversely proportional to the current flowing through the solenoid.
Reason (R) : The magnitude of the magnetic field at a point on the axis of a current carrying solenoid is directly proportional to the number of turns per unit length of a solenoid.
Section E
Read the following passage and answer the questions below : 1 x 5 = 5
The lenses forms different types of images when object placed at different locations. When a ray is incident parallel to the principal axis, then after refraction, it passes through the focus or appears to come from the focus.
When a ray goes through the optical centre of the lens, it passes without any deviation. If the object is placed between focus and optical center of the convex lens, erect and magnified image is formed.
As the object is brought closer to the convex lens from infinity to focus, the image moves away from the convex lens from focus to infinity. Also the size of image goes on increasing and the image is always real and inverted .
A concave lens always gives a virtual, erect and diminished image irrespective to the position of the object.
i) The location of image formed by a convex lens when the object is placed at infinity is a) at focus b) at 2 F c) at optical centre d) between F and 2 F
ii) When the object is placed at the focus of concave lens, the image formed is a) real and smaller b) virtual and inverted c) virtual and smaller d) real and erect
iii) The size of image formed by a convex lens when the object is placed at the focus of convex lens is a) small b) point in size c) highly magnified d) same as that of object
iv) When the object is placed at 2F in front of convex lens, the location of image is
a) at F b) at 2 F on the other side c) at infinity d) between F and optical center
V) At which location of object in front of concave lens, the image between focus and optical centre is formed a) anywhere between centre and infinity b) at F c) at 2 F d) infinity
Section – F
Answer the following question : 5 x7 = 35
Q44. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should the position of the object be relative to the mirror? Draw ray diagram to justify your answer.
Q45. The image of a candle flame placed at a distance of 30 cm from a mirror is formed on a screen placed in front of the mirror at a distance of 60 cm from its pole. What is the nature of the mirror? Find its focal length. If the height of the flame is 2.4 cm, find the height of its image. State whether the image formed is erect or inverted.
Q46 a) Define the following terms in the context of spherical mirrors:
(i) Pole
(ii) Centre of curvature
(iii) Principal axis
(iv) Principal focus
V) Draw ray diagrams to show the principal focus of a Concave mirror
Q47 List the factors on resistance of a conductor depends . Why are metals are good conductor of electricity whereas glass is a bad conductor ? Give reason . Why are alloys are used in heating instruments ?
Q48 . A copper wire has diameter 0.5 mm and resistivity 1.6 × 10-8 Ω m. Calculate the length of this wire to make it resistance 100 Ω. How much does the resistance change if the diameter is doubled without changing its length?
Q49. What is a solenoid? Draw a diagram to show field lines of the magnetic field through and around a current carrying solenoid. State the use of magnetic field produced inside a solenoid. List two properties of magnetic lines of force
Q50 . What is myopia (near-sightedness)? Draw a ray diagram to show how it can be corrected using a lens.
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