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 Physics Questions

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Q:

Temperature can be expressed as derived quantity in terms of any of the following

A) length and mass B) mass and time
C) length,mass and time D) in terms of none
 
Answer & Explanation Answer: D) in terms of none

Explanation:
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Q:

A solid ball of metal has a spherical cavity inside it. When the ball is heated the volume of the cavity will

A) increase B) decrease
C) remain unaffected D) have its shape changed
 
Answer & Explanation Answer: A) increase

Explanation:

The metal ball can be considered  to be made up of several layers of thinner ones. On heating each of these layers will increase in radius. As the inner most layer also increases its radius, the volume inside it i.e, the volume of the hollow portion will also increase.

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Q:

It is more difficult to walk on ice than on a concrete road because 

A) there is very little friction between the ice and feet pressing it B) ice is soft when compared to concrete
C) there is more friction between the ice and feer D) None of these
 
Answer & Explanation Answer: A) there is very little friction between the ice and feet pressing it

Explanation:

It is the friction between the feet and the ground that helps us to walk. Without this friction we would slip and fall

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Q:

Rain drops acquire spherical shape due to 

A) viscosity B) surface tension
C) friction D) elasticity
 
Answer & Explanation Answer: B) surface tension

Explanation:

The Surface tension pulls the surface of the drop equally at all points thus produces the spherical shape having the minimum surface area. This surface tension is the "skin" of a body of water that makes the molecules stick together.

                                 Rain_drops_acquire_spherical_shape_due_to1558074071.png image 

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Q:

Brightness of bulb depends on voltage or current?

A) Current B) Voltage
C) Both A & B D) None
 
Answer & Explanation Answer: C) Both A & B

Explanation:

Brightness of bulb depends on both voltage and current. The brightness depends on power.

Since we know that  Power (P) = Voltage x Current = V I

So whether you increase the current or the voltage the brightness will increase.

 

Example Illustration:

 If you connect a long bulb and a round bulb in series, the long bulb glows but the round bulb does not. Both of them have the same current flowing through them (they are in series) but the long bulb has a greater voltage across it because it has more resistance (even though V= IR is not obeyed exactly, voltage drop does depend on the resistance). If you connect a round bulb and a long bulb in parallel, however, it is the round bulb that is brighter because now the voltage across both bulbs is the same but the current is larger through the round bulb (smaller resistance).

 

Hence, the brightness of a bulb depends on power i.e, both voltage and current.

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Q:

1 Joule is Equal to

A) 10^3 ergs B) 10^6 ergs
C) 10^7 ergs D) 10^5 ergs
 
Answer & Explanation Answer: C) 10^7 ergs

Explanation:

1 Joule = 107 ergs = 0.000239 Kilo Calories.

      • Joule is the Unit of Energy.

Joule is equal to Energy transferred to an object when a force of One Newton acts on that object in the direction of its motion through a distance of one metre.(1 N-m)

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Q:

If a sound travels from air to water, the quantity that remain unchanged is

A) velocity B) frequency
C) wavelength D) amplitude
 
Answer & Explanation Answer: B) frequency

Explanation:
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Q:

Which of the following is/are state function / functions?

1. q + w

2. q

3. w

4. H -TS

Select the correct answer using the code given below.

A) 1 and 4 only B) 1, 2 and 4
C) 2, 3 and 4 D) 1 only
 
Answer & Explanation Answer: A) 1 and 4 only

Explanation:

Q and w are path functions while q+w i.e. H, enthalpy is state function. Similarly, H-TS i.e. G, Gibbs free energy is state function.

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