Physics Questions

Q:

A copper wire of radius r and length lhas a resistance of R. A second copper wire with radius 2r and length lis taken and the two wires  are  joined  in  a  parallel  combination. The  resultant  resistance   of  the  parallel combination of the two wires will be

A) 5 R B) 5 R/4
C) 4 R/5 D) R/5
 
Answer & Explanation Answer: D) R/5

Explanation:

1st copper wire: R = pl/A = pl/ πr2

2ndcopper wire: R’ = p’l’/A’ = pl/(4 πr2) = R/4

If joined in parallel, (1/Req) = (1/R) + (1/R’)

= 1/R + 4/R1/Req= 5/R

Req= R/5

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Q:

A boy is swinging a ball attached to a string in a horizotal circle. If the string snaps 

A) the ball will travel towards the center of the circle and fall down B) it will continue to travel along a tangent to the circle at the point the ball was at the time of snapping and finally fall down
C) it will fall down at the same place where the string breaks D) None of these
 
Answer & Explanation Answer: B) it will continue to travel along a tangent to the circle at the point the ball was at the time of snapping and finally fall down

Explanation:

The centripetal force having been removed the body cannot  execute the curved path

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Q:

What frequency range is the high frequency band?

A) 3 kHz B) 3 to 30 MHz
C) 30 to 300 MHz D) 10 GHz
 
Answer & Explanation Answer: B) 3 to 30 MHz

Explanation:

The HF band is based on frequencies 3 to 30 Mhz. AM radio stations are in the HF band but normally are stated in kilohertz.

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Q:

At what temperature (in Fahrenheit) pure water freezes?

A) 0 B) 17
C) 32 D) 39
 
Answer & Explanation Answer: C) 32

Explanation:

32oFWe know that T(°F) = T(°C) × 1.8 + 3232(°F) = 0(°C)

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10 2746
Q:

The p wave of a normal Electrocardiogram indicates

A) atrial depolarization B) Ventricular repolarization
C) atrial repolarization D) Ventricular depolarization
 
Answer & Explanation Answer: A) atrial depolarization

Explanation:

The P wave in the ECG represents atrial depolarization, which results in atrial contraction, or atrial systole.

The P wave is a summation wave generated by the depolarization front as it transits the atria.

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Q:

Which of the following is Not a form of Energy?

A) Heat B) Sound
C) Motion D) Pressure
 
Answer & Explanation Answer: D) Pressure

Explanation:

Pressure is Not a form of Energy.

 

Energy : It is defined as the ability to do work.

Energy comes in two basic forms. They are :

1. Potential Energy

2. Kinetic Energy

 

Potential Energy is any type of stored energy. It can be chemical, nuclear, gravitational, or mechanical.

Kinetic Energy is found in movement. An airplane flying or a meteor plummeting each have kinetic energy. Even the tiniest things have kinetic energy, like atoms vibrating when they are hot or when they transmit sound waves. Electricity is the kinetic energy of flowing electrons between atoms.

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Q:

The wavelength of a wave is the distance between

A) Crest and Trough B) Crest and Crest
C) Trough and Trough D) Both B & C
 
Answer & Explanation Answer: D) Both B & C

Explanation:

Distance between two Consecutive Crests or two Consecutive Troughs is called Wavelength. But the distance between crest and adjacent trough is half the wavelength.

That is the distance between adjacent crest and trough is called Half the wavelength.

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11 2722
Q:

Which of the following is the best conductor of electricity?

A) Aluminium B) Gold
C) Silver D) Copper
 
Answer & Explanation Answer: C) Silver

Explanation:

silver is the best conductor of electricity.

When compared to remaining 3 metals, as Silver having more number of free electrons in its valency shell it is the good conductor of electricity.

Conductors Thermal Conductivity @ 25degree C

Silver --- 429
Copper --- 401
Gold --- 310
Aluminium --- 250

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