English Medium इयत्ता १० - CBSE Important Questions for Science

What does an electric circuit mean?

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 ______.

Which of the following terms does not represent electrical power in a circuit?

What is meant by "electric power"?

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.

Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source.

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

Define 1 kilowatt hour. 

Write the relation between resistance and electrical resistivity of the material of a conductor in the shape of a cylinder of length `'l'`  and area of cross-section `'A'` . Hence derive the S.I. unit of electrical resistivity.

Resistance of a metal wire of length 5 m is 100 Ω . If the area of cross - section of the wire is `3 × 10^-7  "m"^2` , Calculate the resistivity of the metal . 

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?

Define electric power. An electrical device of resistance R is connected across a source of voltage V and draws a current I. Derive an expression for power in terms of current and resistance.

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.

How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistors R₁, R₂ and R₃ in series connected to a battery of V volts?

Study the following circuit and find out:
      (i) Current in 12 Ω resistor.
      (ii) The difference in the readings of A₁ and A₂, if any.

Write two devices based on the heating effect of electric current.