English Medium Class 10 - CBSE Question Bank Solutions for Science

Unit of electric power may also be expressed as

A uniform magnetic field exists in the plane of paper pointing from left to right as shown in Figure. In the field an electron and a proton move as shown. The electron and the proton experience

In the arrangement shown in Figure  there are two coils wound on a non-conducting cylindrical rod. Initially the key is not inserted. Then the key is inserted and later removed. Then

The substance that will be flattened on beating with a hammer is ______.

Metals are generally solid. Which of the following metals is in the liquid state at room temperature?

A student was asked to perform an experiment to study the force on a current carrying conductor in a magnetic field. He took a small aluminium rod AB, a strong horse shoe magnet, some connecting wires, a battery and a switch and connected them as shown. He observed that on passing current, the rod gets displaced. On reversing the direction of current, the direction of displacement also gets reversed. On the basis of your understanding of this phenomenon, answer the following questions: 

1. Why does the rod get displaced on passing current through it?
2. State the rule that determines the direction of the force on the conductor AB.
3. 1. If the U-shaped magnet is held vertically and the aluminium rod is suspended horizontally with its end B towards due north, then on passing current through the rod from B to A as shown, in which direction will the rod be displaced?
   2. Name any two devices that use current carrying conductors and magnetic fields.

OR

Draw the pattern of magnetic field lines produced around a current carrying straight conductor held vertically on a horizontal cardboard. Indicate the direction of the field lines as well as the direction of current flowing through the conductor.

As shown in the diagram an aluminium rod 'AB' is suspended horizontally between the two poles of a strong horse shoe magnet in such a way that the axis of rod is horizontal and the direction of the magnetic field is vertically upward. The rod is connected in series with a battery and a key.

State giving reason:

1. What is observed when a current is passed through the aluminium rod from end B to end A?
2. What change is observed in a situation in which the axis of the rod 'AB' is moved and aligned parallel to the magnetic field and current is passed in the rod in the same direction?

How is an electric impulse created in human nervous system? 

Why is acidified water considered to be a good conductor of electricity?

A rectangular loop ABCD carrying a current I is situated near a straight conductor XY, such that the conductor is parallel to the side AB of the loop and is in the plane of the loop. If a steady current I is established in the conductor as shown, the conductor XY will ______.

Trace the sequence of events which occur when you suddenly touch a hot object.

Think of situations where receptors do not work properly. What problems are likely to arise?

What will be the amount of energy available to the organisms of the 2nd trophic level of a food chain if the energy available at the first trophic level is 10,000 joules?

Write the number of covalent bonds in the molecule of butane, C₄H₁₀.

Which of the following are always at the second tropic level of food chains?

State with reason any two possible consequences of elimination of decomposers from the Earth.

"Energy flow in a food chain is unidirectional" Justify this statement.

In a food chain of frog, grass, insect and snake, assign trophic level to frog.

What are covalent compounds?