English Medium Class 10 - CBSE Important Questions for Science

State reasons for Myopia. With the help of ray diagrams, show the:

1. image formation by a myopic eye, and
2. correction of myopia using an appropriate lens.

A person is unable to see clearly a poster fixed on a distant wall. He however sees it clearly when standing at a distance of about 2 m from the wall.

1. Draw ray diagram to show the formation of image by his eye lens when he is far away from the wall.
2. List two possible reasons of this defect of vision.
3. Draw ray diagram to show the correction of this defect using appropriate lens.

Observe the following diagram and answer questions following it: 

1. Identify the defect of vision shown.
2. List its two causes.
3. Name the type of lens used for the correction of this defect.

List two difference in the characteristic properties of the virtual images formed by the two types of spherical lenses (concave and convex). How are these characteristics of the two lenses use in the correction of the two common defects of vision namely myopia and hypermetropia?

State the colour which bends:

1. The most.
2. The least while passing through a glass prism.

What does an electric circuit mean?

Define the unit of current.

Redraw the circuit of question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 Ω resistors. What would be the readings in the ammeter and the voltmeter?

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio `"R"/"R'"` is ______.

Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?

 Which instrument is used to measure electric current? How should it be connected in a circuit?

Explain with the help of a labelled circuit diagram how you will find the resistance of a combination of three resistors, or resistance R₁, R₂ and R₃, joined in parallel. Also mention how you will connect the ammeter and the voltmeter in the circuit when measuring the current in the circuit and the potential difference across one of the three resistors of the combination.

Draw a schematic diagram of an electric circuit consisting of a battery of two cells each of 1.5 V, 5 Ω, 10 Ω and 15 Ω resistors and a plug key, all connected in series.

Distinguish between an open and a closed circuit.

State the relation between work, charge and potential difference for an electric circuit.

Consider the sacle of voltmeter shown in the diagram and answer the following questions : 

(a) What is the least count of the voltmeter?

(b) What is the reading shown by the voltmeter ?

(c) If the voltmeter is connected across a resistor of 20 `Omega` how much current is flowing through the resistor?

State the relation correlating the electric current flowing in a conductor and the voltage applied across it. Also, draw a graph to show this relationship.

Answer the following question.
What is the function of a galvanometer in a circuit?

Two electric bulbs rated 100 W; 220 V and 60 W; 220 V are connected in parallel to electric mains of 220 V. Find the current drawn by the bulbs from the mains.