Rays from the sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?

• 15 cm in front of the mirror

• 30 cm in front of the mirror

• between 15 cm and 30 cm in front of the mirror

• more than 30 cm in front of the mirror.

For an object at infinity, a concave mirror produces an image at its focus which is

• enlarged

• virtual

• erect

• real, inverted and diminished

An inverted image can be seen in a convex mirror,

• under no circumstances

• when the object is very far from the mirror

• when the object is at a distance equal to the radius of curvature of the mirror

• when the distance of the object from the mirror is equal to the focal length of the mirror

A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top.

• Plane, convex and concave

• Convex, concave and plane

• Concave, plane and convex

• Convex, plane and concave

In torches, search lights and headlights of vehicles the bulb is placed

• between the pole and the focus of the reflector

• very near to the focus of the reflector

• between the focus and centre of curvature of the reflector

• at the centre of curvature of the reflector

When a ray of light passes from an optically denser medium to a rarer medium, it

• goes undeviated

• bends away from the normal

• bends towards the normal

• None of these

Among identical spheres A and B having charges as - 5 C and - 16 C

• - 5C is at higher potential

• - 16 C is at higher potential

• both are at equal potential

• it cannot be said

Direction of conventional current is from

• Negative terminal to positive terminal

• Positive terminal to negative terminal

• In any direction

• In both the directions

Which of the following statements is true?

• The total mass of the substance remains same in chemical change

• Chemical change is permanent and irreversible

• Physical change is temporary and reversible

• All of these

Which of the following statements is not correct?

• A chemical equation tells us about the substances involved in a reaction.

• A chemical equation informs us about the symbols and formula of substances involved in a reaction

• A chemical equation tells us about the atom or molecules of the reactants and products involved in a reaction

• All are correct