Optics Answers

A particle 'P' moves with velocity 10m/sec towards the intersection point'O' of the 2 plane mirror kept at right angle to each other. I1&I2; are the images formed due to direct reflection from mirror M1 and mirror M2 respectively. Then the relative speed of I1 with respect to I2 will be
(1)20m/sec
(2)12m/sec
(3)10√2m/sec
(4)16m/sec

An object and a plane mirror are shown. Mirror is moved with velocity V at angle Ø. The velocity of the image.
. *
. object(fixed)
. --------------------
. Mirror
(1)2V sinø
(2)2V
(3)2V cosø

9 Two resistances 2Ω and 3Ω are in parallel. The combination is in series with 1.5Ω resistance and a power supply of voltage V. There is a current of 3A through the 2Ω resistance. What are the values of the current I delivered by, and the voltage V across the power supply? (a) 3A and 10.5V (b) 4A and 9V (c) 4A and 12V (d) 12A and 18V
11 A current of 0.5A flowing through a wire produces 21J of heat in 1/2 min. The resistance of the wire is ----------- ohms to 1 place of decimal? (a)2.8Ω (b)3.2Ω (c)1.4Ω (d) 4.6Ω
14 The physical phenomenon which accounts for apparent depth of a pool of water is called? (a)waves (b) polariztion (c) diffraction (d) refraction
15 The ------------ of the eye plays an equivalent role of the screen in optical experiments? (a) lens (b) iris (c) optic nerve (d) retina

12 In an experiment to determine the focal length of a convex lens, 1/u (cmÀ1) was plotted on horizontal and 1/v (cmÀ1) on the vertical axis, where u and v have their usual meaning. What is the physical significance of the reciprocal of the slope of the graph? a) linear magnification (b)focal length (c) object distance (d) image distance
14 In an experiment with a concave mirror, the image of an optical pin which is 4 times its size was cast on on a screen 6m from the object pin. How far from the object pin should the mirror be placed? a) 8m b) 6m c) 3m d) 2m
1 A convex mirror has a radius of 20 cm. An object is placed 30 cm in front of the mirror. Determine where the image will appear. (a) −4.5cm (b) −5.5cm (c) −6.5cm (d) −7.5cm

4 Which of the following is correct about tracing ray digrams with curved mirrors? a) rays incident at the centre of the mirror are reflected through the centre of curvature b) rays passing through the centre of curvature are reflected through the pricipal focus c) rays passing through the pricipal focus are reflected on themselves d) rays parallel and close to the principal axis are reflected through the pricipal focus
5 The null condition in potentiometer experiment shows that? a)the potential difference under test is zero b) current is varying in the circuit c) current is increasing in the circuit d) potential differences are balanced
9 The potentiometer wire plays equivalent role of which of these devices in a circuit? a) rheostat b)thermostat c) galvanometer d) ammeter

1 Diopter is the unit of ? a) linear magnification b) power of lens c) inverse of object distance from lens d) inverse of image distance from lens
2 In an experiment involving the convex lens, , which of the following is NOT correct? a) images must always be sharply focused b) the tip of object pin must be at the same height as the centre of lens c) images obtained must always be magnified d) parallax error must be avoided
3 Describe the image of a candle positioned 20cm in front of a concave mirror of focal length 30cm? a) virtual, inverted, 12cm behind mirror and magnified 3 times b) real, inverted, 12cm in front of mirror and diminished 3 times c) virtual, erect, 60cm behind mirror and magnified 3 time d) real, erect, 60cm in front of mirror and diminished 3 times

16 The potentiometer wire plays equivalent role of which of these devices in a circuit? a) rheostat b) thermostat c) galvanometer d) ammeter (17)The reason we can read print from any direction is that? a) the white part of a page reflects light in all directions b) letters emit black light in all directions. c) letters absorb black light from all directions. d) all of the above (18) In an experiment, potential difference is plotted on the vertical axis and current on the horizontal axis. The slope of the graph represents ? a) resistivity b)conductivity c) resistance d) conductance (19) For a metallic conductor, Ohm's law holds provided? a) potential difference varies b) current remains constant d) temperature remains constant d) potential difference remains constant 20 Calculate the distance and magnification of an object placed 20cm from a converging lens a) 60cm and 0.3 times the size of object b) 20cm and 0.3 times the size of object c) 60cm and 3 times the size of object d) 80cm and 3 times the size of

11 Refraction is a measure of the ------------ as a wave passes from medium to another
a) velocity b) frequency c) wave front d) displacement
12 The image of an object is found to be upright and reduced in size. What type of mirror is used to produce such an image? a) Concave b) Convex c) Both mirrors d) None of the above
13 Convex mirrors are mostly used as? a) magnifying glasses b) driving mirrors c) dentist mirrors d) artist mirrors
14 Which of the following is NOT true of experiments involving curved mirrors? a) image distance is negative for for real image b) object distance is positive c) image distance is negative for virtual image d) focal length is negative for convex mirrors
15 Which of the following is NOT applicable when plotting the graph of experimntal data? a) Lines of best fit should always be used b) circled dots or crosses may be used to show plotted points c) thin, sharp and continuous lines are acceptable d) the scale must be chosen to make the graph occupy as small as

11 Refraction is a measure of the ------------ as a wave passes from medium to another a) velocity b) frequency c) wave front d) displacement