A teacher gives a convex lens and a concave mirror of focal length of about 20 cm each to his student and ask him to find their focal lengths by obtaining the image of a distant object. The student uses a distant tree as the object and obtains its sharp image, one by one, on a screen. The distance d1 and d2 between the lens/mirror and the screen in the two cases and the nature of their respective sharp images are likely to be:(1) (20 cm, 40 cm) and (erect, erect)(2) (20 cm, 40 cm) and (inverted, erect)(3) (20 cm, 20 cm) and (inverted, inverted)(4) (20 cm, 20 cm) and (erect, inverted)

A teacher gives a convex lens and a concave mirror of focal length of

1.	A teacher gives a convex lens and a concave mirror of focal length of about 20 cm each to his student and ask him to find their focal lengths by obtaining the image of a distant object. The student uses a distant tree as the object and obtains its sharp image, one by one, on a screen. The distance d1 and d2 between the lens/mirror and the screen in the two cases and the nature of their respective sharp images are likely to be:(1) (20 cm, 40 cm) and (erect, erect)(2) (20 cm, 40 cm) and (inverted, erect)(3) (20 cm, 20 cm) and (inverted, inverted)(4) (20 cm, 20 cm) and (erect, inverted)
Answer» A teacher gives a convex lens and a concave mirror of focal length of about 20 cm each to his student and ask him to find their focal lengths by obtaining the image of a distant object. The student uses a distant tree as the object and obtains its sharp image, one by one, on a screen. The distance d₁ and d₂ between the lens/mirror and the screen in the two cases and the nature of their respective sharp images are likely to be: (1) (20 cm, 40 cm) and (erect, erect) (2) (20 cm, 40 cm) and (inverted, erect) (3) (20 cm, 20 cm) and (inverted, inverted) (4) (20 cm, 20 cm) and (erect, inverted)