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Write a short note.
Position of isotopes in the Mendeleev’s and the modern periodic table.
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How does the short circuit form? What is its effect?
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Give a scientific reason.
Tungsten metal is used to make a solenoid type coil in an electric bulb.
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Give Scientific reason
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster etc, an alloy such as Nichrome is used, not pure metals.
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Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
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Give Scientific reason.
In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.
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Identify the figure and give its use.

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Identify the figure and give its use.

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Heat energy is being produced in a resistance in a circuit at the rate of 100 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance?
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Solve the following example.
Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
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Who will spend more electrical energy? 500 W TV Set in 30 mins, or 600 W heater in 20 mins?
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An electric iron of 1100 W is operated for 2 hrs daily. What will be the electrical consumption expenses for that in the month of April? (The electric company charges Rs 5 per unit of energy).
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Observe the figure and write accurate conclusion regarding refraction of light.

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What would be the correct order if Zn, Fe, Al and Cu are arranged in increasing order of reactivity?
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Statement 1 : Electric current ( flow of electrons ) creates heat in the resistor.
Statement 2 : Heat in the resistor is created according to the rule of energy conservation.
Explain Statement 1 with the help of Statement 2.
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Statement 1 : Electric current ( flow of electrons ) creates heat in the resistor.
Statement 2 : Heat in the resistor is created according to the rule of energy conservation.
Explain Statement 1 with the help of Statement 2.
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What is the correct reason for blinking / flickering of stars? Explain it.
a) The blasts in the stars.
b) Absorption of star light by the atmosphere.
c) Motion of the stars.
d) Changing refractive index of gases in the atmosphere.
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Find the odd one out and justify it.
Fuse wire, M.C.B., Rubber Gloves, Generator
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Why does tungsten metal used to make solenoid type coil in an electric bulb?
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Observe the following figure which bulb get fuse?

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