Question 1.
State the laws of reflection of light. (AS1)
Ans:Laws of reflection of light is when light falls upon any object surface then the angle of reflection is equal to the angle of incidence.
Question 2.
How do you find the focal length of a concave mirror? (AS1)
Ans:For finding out the length of the concave mirror the mirror and the screen should be at the same height. The distance between the pole and the converging point of parallel rays is called the focal length.
Question 3.
Where will the image form when we place an object, on the principal axis of a concave mirror at a point between focus and centre of curvature? (AS1)
Ans:If an object is placed on the principal axis of a concave mirror at point between focus and centre of curvature then the image will form beyond the centre of curvature.
Question 4.
Find the distance of the image when an object is placed on the principal axis at a distance of 10cm in front of a concave mirror whose radius of curvature is 8 cm. (AS1)
Ans:we know the mirror formula, 1/u +1/v = 1/f
From the question we get, u=-10cm; R= 8cm, R=2f then f= -4cm
1/v -1/10=1/-4. Or v= -20/3 cm.
Question 5.
State the differences between convex and concave mirrors. (AS1)
Ans:In a convex mirror the image always is virtual and erect. But in a concave mirror, the image always is virtual.
Question 6.
Distinguish between real and virtual images. (AS1)
Ans:
The virtual image is formed because of the intersection of imaginary light whereas real images are formed as a result of the actual intersection of light.
Question 7.
How do you get a virtual image using a concave mirror? (AS1)
Ans:In a concave mirror if an objective is kept between the pole and focus then which image is formed are called a virtual image.
Question 8.
What do you know about the terms given below related to spherical mirrors? (AS1)
| (a) Pole |
(b) Centre of curvature |
(c) Focus |
| (d) Radius of curvature |
(e) Focal length. |
(f) Principal axis |
| (g) Object distance |
(h) Image distance |
(i) Magnification |
Ans: (a) Pole: Pole lies on the mirror surface. It’s called the spherical mirror reflecting surface centre.
(b) Centre of curvature: It is the centre of the spherical mirror.
(c) Focus: After reflection where the parallel lines meet on the principal axis is called the focus.
(d) Radius of curvature: The distance between the pole and centre of curvature of a spherical mirror is called the radius of curvature.
(e) Focal length: The distance between the pole and focus of a spherical mirror is called the focal length.
(f) Principal axis: The lines which it passes through the centre of a spherical mirror is called the principal axis.
(g) Object distance: The total distance between where the object is situated and the pole of the mirror is the object distance.
(h) Image distance:-The distance from where the image formed and the Pole of a spherical mirror is called the image distance.
(i) Magnification: The negative ratio of image and object distance of a spherical mirror is called the magnification of a mirror.
Question 9.
Write the rules for sign convention. (AS1)
Ans:When we measure distance along in the direction of incident light are always taken positive and the opposite of the direction we must take negatively.
Question 10.
The magnification produced by a plane mirror is +1. What does this mean? (AS1)
Ans:For the value of magnification +1 we concluded that the image will be virtual and erect as well as the same object.
Question 11.
Imagine that spherical mirrors were not known to human beings. Guess the consequences.(AS2)
Ans:If the spherical mirror were unknown to the people then there will be very much effect on hospitality, rare view, microscopic. Especially the use of concave and concave mirror was unknown to us.
Question 12.
By observing steel vessels and different images in them; Surya, a third class student, asked his elder sister Vidya some questions. What may be those questions? (AS2)
Ans:The expected questions that may be asked by Suriya to his sister is the image which seen in the vessel is called what, why the image is inverted, why there are different sizes of different objects.
Question 13.
How do you verify the 1st law of reflection of light with an experiment? (AS3)
Ans:With the help of laser light when we make it incident through the plane mirror, we can see that the reflected ray, incident ray and normal rays all are in the same plane. So by this incident, we verify the 1st law of reflection of light.
Question 14.
How do you verify the 2nd law of reflection of light with an experiment? (AS3)
Ans:-At the first draw, a straight line AB from that draw a normal OM on it then make line XO which is at an angle to normal at O and after that, you will find an image of it on another side mirror named it OX’ . Therefore you will get the angle made by OX and OX’ are equal which is incident and reflected angle.
Question 15.
What do you infer from the experiment which you did with concave mirrors and measured the distance of object and distance of image? (AS3)
Ans:With the help of the experiment of the concave mirror we infer that concave mirror always formed real and virtual images.
Question 16.
Find the plane of the reflection experimentally for the incident ray which passes through the heads of the pins pierced in front of the mirror. (AS3)
Ans:For the finding of plane reflection we need a mirror strip, drawing board, pencil, pin, clamps, white paper etc.
Question 17.
Collect information about the history of spherical mirrors in human civilization. Display it in your classroom. (AS4)
Ans:At an early stage when mirrors manufactured were polished stone prices. The Chinese made the mirror in 500AD with the help of silver-mercury amalgam. Ptolemy also did many experimentson the iron polished mirror at that time.
Question 18.
Think about the objects which act as a concave or convex mirror in your surroundings. Make a table and display it in your classroom. (AS4)
Ans:The concave mirror uses in our daily life are headlights of different vehicles, shaving mirrors, the mirror used by dentists. And the convex mirror is rare view mirror, streetlights, glass water surfaces.
Question 19.
How will our image be in concave and convex mirrors? Collect photographs and display in your classroom. (AS4)
Ans:In a concave mirror our image will show inverted when we are at some distance from the mirror but in a convex mirror our image will show small in size and upright located at the focal point.
Question 20.
Draw and explain the process of formation of image with a pinhole camera? (AS5)
Ans:
The camera of the pinhole are simple but no lenses in there. The box is lightproof and kept in a dark room, a small hole at one side of it. When the light passes through a hole an inverted image will form on the opposite side of the box.
Question 21.
Draw suitable rays by which we can guess the position of the image formed by a concave mirror.
Ans:The rays which are parallel to the principal axis will be reflected and the rays will pass through the focus of the concave mirror.
Question 22.
Show the formation of image with a ray diagram when an object is placed on the principal axis of a concave mirror away from the centre of curvature. (AS5)
Ans:
The image of the objet away from the centre of curvature will be formed on the focus of the principal axis of a concave mirror.