Human Eye and Colourful World — Science STD 10 — Question

The resistivity does not change if:

1. The material is changed.
2. The temperature is changed.
3. The shape of the resistor is changed.
4. Both material and temperature are changed.

In myopia:

The back face of a circular loop of wire is found to be south magnetic pole. The direction of current in this face of the circular loop of wire will be:

1. Towards south.
2. Clockwise.
3. Anticlockwise.
4. Towards north.

n normal use, a current of 3.5A flows through a hair dryer. Choose a suitable fuse from the following:

A glass slab is placed over a page on which the word VIBGYOR is printed with each letter in corresponding colour. Then, which of the following is correct?

Choose the incorrect statement from the following regarding magnetic lines of field:

1. The direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points.
2. Magnetic field lines are closed curves.
3. If magnetic field lines are parallel and equidistant, they represent zero field strength.
4. Relative strength of magnetic field is shown by the degree of closeness of the field lines.

An AC source has a frequency of 50Hz. The number of times, its direction changes in one second is:

One atomic mass unit (u) is equivalent to an energy of:

1. 931eV.
2. 9.31MeV.
3. 1MeV.
4. 931MeV.

Which of the following correctly describes the magnetic field near a long straight wire?

A student sitting on the last bench in the class cannot read the writing on the blackboard clearly but he can read the book lying on his de clearly. Which of the following statement is correct about the student?

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