Refraction at curved surfaces
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364808 A convex lens forms a real image \(9\;cm\) long on a screen. Without altering the position of the object and the screen, the lens is displaced and we get again a real image \(4\;cm\) long on the screen. Then the length of the object is-

1 \(9\;cm\)
2 \(4\;cm\)
3 \(6\;cm\)
4 \(36\;cm\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364809 A candle placed \(25\;cm\) from a lens forms an image on a screen placed \(75\;cm\) on the other side of the lens. The focal length and type of the lens should be

1 \( + 18.75\;cm\) and convex lens
2 \( - 18.75\;cm\) and concave lens
3 \( + 20.25\;cm\) and convex lens
4 \( - 20.25\;cm\) and concave lens
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364810 A convex lens produces a real image \(m\) times the size of the object. What will be the object distance from the lens?

1 \(\left( {m - 1} \right)f\)
2 \(\left( {\frac{{m + 1}}{m}} \right)f\)
3 \(\frac{{m + 1}}{f}\)
4 \(\left( {\frac{{m - 1}}{m}} \right)f\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364811 A thin lens has focal length, \(f\) and its aperture has diametert forms an image of intensity \(I\). Now the central part of the aperture upto diameter \(\frac{d}{2}\) is blocked by an opaque paper. The focal length and image intensity will change to

1 \(f\) and \(\frac{{3I}}{4}\)
2 \(f\) and \(\frac{I}{4}\)
3 \(\frac{{3f}}{4}\) and \(\frac{I}{2}\)
4 \(\frac{f}{2}\) and \(\frac{I}{2}\)
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PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364808 A convex lens forms a real image \(9\;cm\) long on a screen. Without altering the position of the object and the screen, the lens is displaced and we get again a real image \(4\;cm\) long on the screen. Then the length of the object is-

1 \(9\;cm\)
2 \(4\;cm\)
3 \(6\;cm\)
4 \(36\;cm\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364809 A candle placed \(25\;cm\) from a lens forms an image on a screen placed \(75\;cm\) on the other side of the lens. The focal length and type of the lens should be

1 \( + 18.75\;cm\) and convex lens
2 \( - 18.75\;cm\) and concave lens
3 \( + 20.25\;cm\) and convex lens
4 \( - 20.25\;cm\) and concave lens
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364810 A convex lens produces a real image \(m\) times the size of the object. What will be the object distance from the lens?

1 \(\left( {m - 1} \right)f\)
2 \(\left( {\frac{{m + 1}}{m}} \right)f\)
3 \(\frac{{m + 1}}{f}\)
4 \(\left( {\frac{{m - 1}}{m}} \right)f\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364811 A thin lens has focal length, \(f\) and its aperture has diametert forms an image of intensity \(I\). Now the central part of the aperture upto diameter \(\frac{d}{2}\) is blocked by an opaque paper. The focal length and image intensity will change to

1 \(f\) and \(\frac{{3I}}{4}\)
2 \(f\) and \(\frac{I}{4}\)
3 \(\frac{{3f}}{4}\) and \(\frac{I}{2}\)
4 \(\frac{f}{2}\) and \(\frac{I}{2}\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364808 A convex lens forms a real image \(9\;cm\) long on a screen. Without altering the position of the object and the screen, the lens is displaced and we get again a real image \(4\;cm\) long on the screen. Then the length of the object is-

1 \(9\;cm\)
2 \(4\;cm\)
3 \(6\;cm\)
4 \(36\;cm\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364809 A candle placed \(25\;cm\) from a lens forms an image on a screen placed \(75\;cm\) on the other side of the lens. The focal length and type of the lens should be

1 \( + 18.75\;cm\) and convex lens
2 \( - 18.75\;cm\) and concave lens
3 \( + 20.25\;cm\) and convex lens
4 \( - 20.25\;cm\) and concave lens
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364810 A convex lens produces a real image \(m\) times the size of the object. What will be the object distance from the lens?

1 \(\left( {m - 1} \right)f\)
2 \(\left( {\frac{{m + 1}}{m}} \right)f\)
3 \(\frac{{m + 1}}{f}\)
4 \(\left( {\frac{{m - 1}}{m}} \right)f\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364811 A thin lens has focal length, \(f\) and its aperture has diametert forms an image of intensity \(I\). Now the central part of the aperture upto diameter \(\frac{d}{2}\) is blocked by an opaque paper. The focal length and image intensity will change to

1 \(f\) and \(\frac{{3I}}{4}\)
2 \(f\) and \(\frac{I}{4}\)
3 \(\frac{{3f}}{4}\) and \(\frac{I}{2}\)
4 \(\frac{f}{2}\) and \(\frac{I}{2}\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364808 A convex lens forms a real image \(9\;cm\) long on a screen. Without altering the position of the object and the screen, the lens is displaced and we get again a real image \(4\;cm\) long on the screen. Then the length of the object is-

1 \(9\;cm\)
2 \(4\;cm\)
3 \(6\;cm\)
4 \(36\;cm\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364809 A candle placed \(25\;cm\) from a lens forms an image on a screen placed \(75\;cm\) on the other side of the lens. The focal length and type of the lens should be

1 \( + 18.75\;cm\) and convex lens
2 \( - 18.75\;cm\) and concave lens
3 \( + 20.25\;cm\) and convex lens
4 \( - 20.25\;cm\) and concave lens
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364810 A convex lens produces a real image \(m\) times the size of the object. What will be the object distance from the lens?

1 \(\left( {m - 1} \right)f\)
2 \(\left( {\frac{{m + 1}}{m}} \right)f\)
3 \(\frac{{m + 1}}{f}\)
4 \(\left( {\frac{{m - 1}}{m}} \right)f\)
PHXII09:RAY OPTICS AND OPTICAL INSTRUMENTS

364811 A thin lens has focal length, \(f\) and its aperture has diametert forms an image of intensity \(I\). Now the central part of the aperture upto diameter \(\frac{d}{2}\) is blocked by an opaque paper. The focal length and image intensity will change to

1 \(f\) and \(\frac{{3I}}{4}\)
2 \(f\) and \(\frac{I}{4}\)
3 \(\frac{{3f}}{4}\) and \(\frac{I}{2}\)
4 \(\frac{f}{2}\) and \(\frac{I}{2}\)