A Numerical from Combination of thin lenses in contact

Two thin lenses of focal lengths f1=20cm and f2=60cm are placed in contact. find the focal length f3 of the combined lenses. find also the focal length f of a third lens placed in contact with these two that would result in overall focal length f11=-40cm. (Asked Young) Incoming search terms:class 9 science sample paper for [...]

Why the ray of light passing through optical center of a lens passes undeviated while when it passes through other points on the interface of the lens, it gets refracted?

Deviation is the change in direction of the ray while passing through the lens. The middle portion of the lens is comparatively flat and there is a point on the principal axis and inside the sphere read more

Commonly asked questions for AISSE (CLASS X CBSE) Physics (Set – 1)

(Collected from Previous Board Question Papers and CBSE Sample Papers andGuess Papers made by experienced teachers)

Where does centre of curvature of a spherical mirror lie? Name two important properties of a magnet. How is 1 ohm related to ampere and volt? Draw neat ray diagrams to illustrate the formation of images due to a beam of light incident parallel to the principal axis of a (i) concave mirror, (ii) convex mirror in each case. Why is a series arrangement not used for connecting domestic electrical appliances in a circuit? Out of 60 W and 40 W lamps, which one has a higher electrical resistance when in use? Draw ray diagrams to represent the nature, position and relative size of the image formed by a convex lens for the object placed.(a) at F (b) Between F and O What is meant by the term, ‘magnetic field’? Why does a compass needle show deflection when brought near a bar magnet? Two lamps, one rated 60W at 220 V and the other 40W at 220 V, are connected in parallel to the electric supply at 220V.(a) Draw a circuit diagram to show the connections.

(b)Calculate the current drawn from the electric supply.

(c)Calculate the total energy read more