Electricity — Science STD 10 — Question

Motion of charges is nothing but:

 By which instrument, the presence of magnetic field be determined?

A battery and three lamps are connected as shown?

 

Which of the following statements about the currents at X, Y and Z is correct?

1. The current at Z is greater than that at Y.
2. The current at Y is greater than that at Z.
3. The current at X equals the current at Y.
4. The current at X equals the current at Z.

On the basis of their experiment, "To trace the path of a ray of light through a rectangular glass slab," students of a class arrived at which one of the following conclusions:

A convex lens of focal length 10cm is placed in contact with a concave lens of focal length 20cm. The focal length of this combination of lenses will be:

1. +10cm
2. +20cm
3. -10cm
4. -20cm

In the following circuits (Figure), heat produced in the resistor or combination of resistors connected to a 12V battery will be:

A student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his text book. Which of the following statements is correct?

1. The near point of his eyes has receded away.
2. The near point of his eyes has come closer to him.
3. The far point of his eyes has come closer to him.
4. The far point of his eyes has receded away.

Two big mirrors A and B are fitted side by side on a wall. A man is standing at such a distance from the wall that he can see the erect image of his face in both the mirrors. When the man starts walking towards the mirrors, he find that the size of his face in mirror A goes on increasing but that in mirror B remains the same.

An electron is moving towards east in a magnetic field acting vertically downwards. So the electron is deflected towards:

A spherical mirror and a thin spherical lens have each a focal length of -15 cm. The mirror and the lens are likely to be.