An object is placed 20 cm in front of a concave mirror of a radius of curvature 10 cm. The position of the image from the pole of the mirror is:
1. 7.67 cm
2. 6.67 cm
3. 8.67 cm
4. 9.67 cm
An object is at a distance of 30 cm in front of a concave mirror of focal length 10 cm. The image of the object will be:
1. | smaller in size. |
2. | inverted. |
3. | between the focus and centre of curvature. |
4. | All of the above. |
Match the corresponding entries of Column-1 with Column-2. (Where \(m\) is the magnification produced by the mirror)
Column-1 | Column-2 | ||
A. | \(m= -2\) | I. | convex mirror |
B. | \(m= -\frac{1}{2}\) | II. | concave mirror |
C. | \(m= +2\) | III. | real Image |
D. | \(m= +\frac{1}{2}\) | IV. | virtual Image |
A | B | C | D | |
1. | I & III | I & IV | I & II | III & IV |
2. | I & IV | II & III | II & IV | II & III |
3. | III & IV | II & IV | II & III | I & IV |
4. | II & III | II & III | II & IV | I & IV |
When a concave mirror of focal length f is immersed in water, its focal length becomes f', then:
1. | f'=f |
2. | f'<f |
3. | f'>f |
4. | The information is insufficient to predict |
A \(4.5~\text{cm}\) needle is placed \(12~\text{cm}\) away from a convex mirror of focal length \(15~\text{cm}\). What is the magnification?
1. \(0.5\)
2. \(0.56\)
3. \(0.45\)
4. \(0.15\)
A concave mirror gives an image three times as large as the object placed at a distance of 20 cm from it. For the image to be real, the focal length should be:
1. | 10 cm | 2. | 15 cm |
3. | 20 cm | 4. | 30 cm |
A convex mirror of focal length \(f\) forms an image which is \(\frac{1}{n}\) times the length of the object. The distance of the object from the mirror is:
1. \((n-1)f\)
2. \(\left( \frac{n-1}{n} \right)f\)
3. \(\left( \frac{n+1}{n} \right)f\)
4. \((n+1)f\)
A thin rod of length \(\frac{f}{3}\) lies along the axis of a concave mirror of focal length \(f\). One end of its magnified, real image touches an end of the rod. The length of the image is:
1. \(f\)
2. \(\frac{f}{2}\)$$
3. \(2f\)
4. \(\frac{f}{4}\)$$
A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in such a way that its end closer to the pole is 20 cm away from the mirror. The length of the image is:
1. | 10 cm | 2. | 15 cm |
3. | 2.5 cm | 4. | 5 cm |
The distance between the object and its real image formed by a concave mirror is minimum when the distance of the object from the centre of curvature of the mirror is: [f $\to $ focal length of the mirror]
1. Zero
2. $\frac{\mathrm{f}}{2}$
3. f
4. 2f