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In the circuit shown in Fig., when the key is closed, the compass needle placed in the matchbox deflects. Name the force which causes this deflection.

Answer: When the switch is closed, current flows through the wire, creating a magnetic field surrounding the wire, which exerts a magnetic... View Article

In the figure of the human eye, the cornea is represented by the letter (a) A (b) B (c) C (d) D

Answer: (c) C The human eye is triple-layered. The three layers are sclera, choroid and retina. The sclera is the outermost layer of dense... View Article

In the given Fig. out of the positions A, B, C and D which will indicate the position of the sun? Draw the sun at the appropriate position.

Answer: The Sun will be in the C position. It can be identified as the illuminated side of the Earth at position C, which has day, and the... View Article

In the purification of copper, a thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transfered to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?

Answer: Because electric current dissociates copper and sulphate when passed through the copper sulphate solution, the thick rod of impure copper... View Article

In triangle ABC, right-angled at B, if tan A = 1/√3 find the value of: (i) sin A cos C + cos A sin C (ii) cos A cos C – sin A sin C

Given, in ∆ABC right angled at B, tan a= √3 Let ΔABC in which ∠B=90° tan A = BC/AB = 1/√3 Let us consider; BC = 1k AB = √3 k Where k is... View Article

Is 8/9 the multiplication inverse of -1(1/8). Why or why not?

Answer: The multiplicative inverse of a number N is represented by 1/N or N-1. It is also called reciprocal, derived from the Latin word... View Article

Is it possible to predict the occurrence of an earthquake?

Answer: No, it is impossible to predict when an earthquake will occur. An earthquake is the shaking of the surface of Earth due to the... View Article

Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.

Answer: No, conducting electrical repairs during a heavy downpour is extremely dangerous for an electrician. Rather, it is highly dangerous... View Article

Is the distilled water acidic/basic/neutral? How would you verify it?

Answer: Distilled water is a pure type of water that does not contain any ions. It is a compound made up of hydrogen and oxygen. We can say that... View Article

Is there a force of friction between the wheels of a moving train and iron rails? If yes, name the type of friction. If an air cushion can be introduced between the wheel and the rail, what effect will it have on the friction?

Answer: Yes, there is always friction between a moving train's wheels and the iron rails. Because the wheels are rolling on the track, this... View Article

It is difficult to cut cloth using a pair of scissors with blunt blades. Explain.

Answer: Cutting cloth with a pair of scissors with blunt blades is difficult since blunt blades have a larger surface area and thus provide less... View Article

It is much easier to burst an inflated balloon with a needle than by a finger. Explain.

Answer: Because the needle tip has a much smaller cross-section than our finger, and we know that pressure imposed by a force is inversely... View Article

John saw the full moon on a particular day. After how many days will he be able to see the full moon again?

Answer: A lunar cycle is completed in a month that is the size of the moon from zero to the full moon stage and back to. If John sees a full moon... View Article

Light is falling on surface S1, S2, S3 as shown in Fig.. Surfaces on which the angle of incidence is equal to the angle of reflection is/are (a) S1 only (b) S1 and S2 only (c) S2 and S3 (d) all the three surfaces

Answer: (d) all the three surfaces Laws of reflection are always followed irrespective of the surface of the object hence the angle of... View Article

Lightning can be seen as the moment it occurs. Paheli observes lightning in her area. She hears the sound 5 s after she observed lightning. How far is she from the place where lightning occurs? (speed of sound = 330 m/s).

Answer: 1650m Sound travels at a significantly slower rate than light. Sound travels at a speed of around 340 metres per second in air. Light... View Article

List three states in India where earthquakes are more likely to strike.

Answer: Gujarat, Assam and Jammu & Kashmir are the three states where an earthquake is more likely to strike. An earthquake zone is... View Article

Look at Fig. Can the image of the child in it be obtained on a screen?

Answer: Because the image of the child is not real, it cannot be obtained on the screen. Because the images formed by a plane mirror are... View Article

Look at Fig. carefully and answer the following question: (a) In which part of the sky would you see the full moon in the evening? (b) In which part of the sky would you see the crescent moon in the evening?

Answer: We see the full moon in the evening in the eastern part of the sky. Full moon - The full moon is one of the phases of the moon when... View Article

Major earthquakes are less likely to occur in (a) North East India (b) Rajasthan (c) Rann of Kutch (d) Orissa

Answer: (d) Orissa In Orissa, major earthquakes are less likely to occur. Kashmir, the Western and Central Himalayas, the entire North-East, the... View Article

Mark ‘T’ if the statement is true and ‘F’ if it is false: (i) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F) (ii) Tooth decay is caused by the presence of a base. (T/F)

Answer: (i) Indicator is a substance which shows different colours in acidic and basic solutions - True (T) Acidic and basic substances abound in... View Article

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