The image formed by a concave lens for an object at infinity is:
virtual, erect, and point-sized
A concave lens is a diverging lens: parallel rays coming from an object at infinity spread out after passing through it, and only their backward extensions appear to meet. They appear to diverge from the focus on the same side as the object, so the image is always virtual and erect, never real.
When the object is at infinity, the rays converge (in their virtual extension) to the focal point F of the concave lens, so the image is formed at the focus and is reduced to a point. Hence it is virtual, erect, and point-sized.
"real, inverted, and large" and "real, erect, and magnified" are wrong because a concave lens can never form a real image of a real object. "virtual, inverted, and diminished" is wrong because a concave lens always gives an erect (not inverted) image.
Hence, the image is virtual, erect, and point-sized.
Which of the following is NOT the correct use of a concave mirror?
An object is placed at a distance of 40 cm from a convex lens of focal length 10 cm, such that an image is formed at a distance of X cm from the lens. What is the value of X?
When a parallel beam of light passes through a convex lens, after refraction it:
An image is formed at a distance of 30 cm from a convex mirror when the object is placed 40 cm from the mirror. The magnification produced by the mirror will be _______.
A science fair project uses a convex mirror to monitor a hallway. If a person stands at various distances from the mirror, what remains constant about the images formed, regardless of their position?
A student observes that the image formed by a lens is twice the size of the object and is real. Where is the object placed relative to the lens?
How is the object distance measured in the sign convention for spherical lenses?
The magnification of a concave mirror is −1. Which of the following statements is correct about the position of the object?
The power of a lens is given as the reciprocal of its:
A ray of light enters a rectangular glass slab from air at an angle of 40 degrees to the normal. If the refractive index of glass with respect to air is 1.5 and the velocity of light in air is \(3 \times 10^{8}\) m/s, what is the velocity of light inside the glass slab?
A convex lens of focal length f will form a magnified real image of an object, if the object is placed.
A ray of light travelling in the direction \(\frac{1}{2} (\hat i + \sqrt 3 \hat j)\) is incident on a plane mirror. After reflection it travels along the direction \(\frac{1}{2} (\hat i - \sqrt 3 \hat j)\) The angle of incidence is:
Twinkling of stars is due to atmospheric
An optical fibre has a core material of refractive index of 1.55 and cladding material of refractive index of 1.50. The numerical aperture of the fibre is