English Medium इयत्ता १० - CBSE Important Questions for Science

Explain the following term related to spherical lenses: focal length

The laws of reflection hold true for ______.

An object of height 10 cm is placed 25 cm away from the optical centre of a converging lens of focal length 15 cm. Calculate the image distance and height of the image formed.

Describe an activity to show that colours of white light splitted by a glass prism can be recombined to get white light by another identical glass prism. Also draw ray diagram to show the recombination of the spectrum of white light.

State the cause of dispersion of white light passing through a glass prism. How did Newton show that white light of sun contains seven colours using two identical glass prisms. Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the focus of the first prism.

When we place a glass prism in the path of a narrow beam of white light a spectrum is obtained. What happens when a second identical prism is placed in an inverted position with respect to the first prism? Draw a labelled ray diagram to illustrate it.

A student cannot see a chart hanging on a wall placed at a distance of 3 m from him. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagrams for the (i) defect of vision and also (ii) for its correction.

In the following diagram showing dispersion of white light by a glass prism, the colours 'P' and 'Q’ respectively are:  

Two metallic spheres A and B kept on insulating stands are in contact with each other. A positively charged  rod P is brought near the sphere A as shown in the figure. The two spheres are separated from each other,  and the rod P is removed. What will be the nature of charges on spheres A and B?

A metal sphere is kept on an insulting stands. A negatively charged rod is brought near it, then the sphere is  earthed as shown. On removing the earthing, and taking the negatively charged rod away, what will be the  nature of charge on the sphere? Give reason for your answer. 

Solve the following question:
In an electric circuit, two resistors of 12 0 each are joined in parallel to a 6 V battery. Find the current drawn from the battery.

Let the resistance of an electrical device remain constant, while the potential difference across its two ends decreases to one fourth of its initial value. What change will occur in the current through it? State the law which helps us in solving the above stated question. 

Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?

Draw the pattern of magnetic field lines of a solenoid through which a steady current flows. What does the pattern of field lines inside the solenoid indicate?

Draw magnetic field lines produced around a straight current carrying conductor passing through a cardboard. How will the strength of the magnetic field change when the point where magnetic field is to be determined is moved away from the conductor?

When is the force experienced by a current-carrying straight conductor placed in a uniform magnetic field.

1. Maximum
2. Minimum

An alpha particle enters a uniform magnetic field as shown. The direction of force experienced by the alpha particle is ______.

For the current carrying solenoid as shown, draw magnetic field lines and give reason to explain that out of the three points A, B and C, at which point the field strength is maximum and at which point it is minimum? 

• Assertion: A compass needle is placed near a current-carrying wire. The deflection of the compass needle decreases when the magnitude of the current in the wire is increased.
• Reason: The strength of a magnetic field at a point near the conductor increases by increasing the current.

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