Sign Convention

Q.

In which mirror magnification is negative?

Q.

u – object distance

v – image distance

f – focal length

R – radius of curvature

Choose the option which shows correct sign convention?

1. v = – ve, u = – ve, f = + ve, R = + ve, h = + ve, h’ = – ve

2. v = – ve, u = – ve, f = – ve, R = + ve, h = + ve, h’ = – ve

3. v = + ve, u = + ve, f = + ve, R = + ve, h = + ve, h’ = – ve

4. v = – ve, u = – ve, f = – ve, R = – ve, h = + ve, h’ = – ve

Q.

(a) The magnification is positive for all virtual images and is negative for all real images.

(b) The magnification of the concave lens and convex mirror is always positive whereas the magnification of the convex lens and concave mirror can be positive or negative depending on the position of the object before the lens.

1. Only (a) is true

2. Only (b) is true

3. Both (a) and (b) are true

4. Both (a) and (b) are false

Q. Both concave and convex mirrors can produce virtual and erect images. A concave mirror is used as a shaving mirror, but a convex mirror is not. Why?

1. The virtual image formed by a concave mirror is enlarged, whereas that formed by a convex mirror is diminished.
2. The virtual image formed by a convex mirror is enlarged, but that formed by a concave mirror is diminished.
3. The virtual image formed by a convex mirror is at infinity.
4. The virtual image formed by a concave mirror is brighter.

Q.

According to Cartesian sign convention, which of the following is/are true?

1. The focal length of the concave mirror is positive and the focal length of the convex mirror is negative.

2. The focal length of the concave mirror is negative and the focal length of the convex mirror is positive.

3. All distances are measured from the pole of the mirror.

4. The focal length of the concave mirror and the convex mirror is negative.

Q.

The magnification produced by a concave mirror

1. is always more than one

2. is always less than one

3. is always equal to one

4. may be less than or greater than one.

Q.

For an inverted image, height of the image is ______.

1. positive

2. negative

3. zero

4. not defined

Q.

A concave mirror and a plane mirror are arranged facing each other and an object $AB$ is placed between them as shown in the figure. What is the distance between the object and its inverted, virtual image formed in the plane mirror?

Q.

Magnification of image formed by a pinhole camera is the ratio of?

1. The size of the object to that of the image

2. The size of the image to that of the object

3. The distance between the image and the pinhole to the height of the image.

Q.

The focal length of a mirror is 15cm, Identify the type of mirror.

1. Concave mirror

2. Convex mirror

3. Plane mirror

4. Cylindrical mirror

Q. Which property of concave mirror is utilised in using it as a shaving mirror?

Q. According to New Cartesian Sign Convention:

(a) focal length of concave mirror is positive and that of convex mirror is negative
(b) focal length of both concave and convex mirrors is positive
(c) focal length of both concave and convex mirrors is negative
(d) focal length of concave mirror is negative and that of convex mirror is positive

Q.

A concave mirror produces three times enlarged image of an object placed at $10\mathrm{cm}$ in front of it. Calculate the focal length of the mirror.

Q.

If AB is the object and CD is the image formed. If AP is the object distance and CP is the image distance from the mirror. Then choose the correct sign convention?
$\begin{array}{cc}\text{1. height of image}=+ve& \text{2. height of image}=-ve\\ \text{3. height of object}=+ve& \text{4. height of object}=-ve\\ \text{5. AP}=+ve& 6.AP=-ve\\ \text{7. PC}=+ve& 7.PC=+ve\end{array}$

1. concave mirror – 1, 3, 5 & 7, plane mirror – 1, 3, 5, 7

2. concave mirror – 2, 3, 6 & 8, plane mirror – 1, 3 , 6 , 7

3. concave mirror – 2, 3, 6 & 8, plane mirror – 1, 3, 6, 8

4. concave mirror – 2, 3, 5, 7, plane mirror – 1, 3, 6,

Q.

AB refers to an object and CD is its image formed. If AP and CP are the object and image distances from the mirror, choose the correct sign convention:
$\begin{array}{cc}1.\text{height of image}=+\text{ve}& 2.\text{height of image}=-\text{ve}\\ 3.\text{height of object}=+\text{ve}& 4.\text{height of object}=-\text{ve}\\ 5.\text{AP}=+\text{ve}& 6.\text{AP}=-\text{ve}\\ 7.\text{PC}=+\text{ve}& 7.\text{PC}=+\text{ve}\end{array}$

1. concave mirror – 2, 3, 6 & 8, plane mirror – 1, 3, 6, 8

2. concave mirror – 2, 3, 5, 7, plane mirror – 1, 3, 6,

3. concave mirror – 1, 3, 5 & 7, plane mirror – 1, 3, 5, 7

4. concave mirror – 2, 3, 6 & 8, plane mirror – 1, 3 , 6 , 7

Q.

a virtual, erect and magnified image of an object is to be produced with a concave mirror of focal length 15cm. which of the following object distance should be chosen for this purpose?

10cm , 16cm , 20cm

Q. Which of the following statements is correct according to New Cartesian Sign Convention?

1. Focal length of a concave mirror is positive and that of a convex mirror is negative.
2. Focal length of a concave mirror is negative and that of a convex mirror is positive.
3. Image distance is always positive for a concave mirror.
4. The height of all the real and inverted images is positive.

Q. A light ray is incident normally on a plane mirror.What is the direction of the reflected ray? Show it by a labelled diagram.

Q.

For an inverted image, height of the image is ___________.

1. Positive

2. Negative

3. Not defined

4. Zero

Q. Write the sign convection used for spherical mirror .