Physics Questions & Answers - Free Online Practice

1,426.

The two liquids which are often used in thermometer on experiment basic is known as

Mercury only

Alcohol and Water

Mercury and Alcohol

Alcohol only

Correct answer is C

Mercury and alcohol are often used in THERMOMETER

Note:Water is never allowed to be used in thermometer because, it doesn’t expand uniformly

1,427.

Transformers are designed so that energy losses are reduced to a minimum. This is achieved through which of these process?

I. Using a soft iron ore
II. Laminating the iron core to reduce energy loses due to eddy current
III. Designing an efficient iron core

I & II only

II only

I, II, & III only

III only

View answer & explanation

Correct answer is C

Fig (I) (II) (III) are they in which a transformer was designed to reduce an energy loses by reducing through this collective designed or efforts

1,428.

Which of the following will increase the boiling point of water?

I. Taking it to a high altitude
II. Dissolving a salt into it
III. Heating it in a sealed flask
IV. Increasing the rate of heat supply

.

I only

III & IV only

II & III only

II only

View answer & explanation

Correct answer is C

The simplest way to change the boiling point of a liquid is to change the surrounding pressure. (a) Using a closed system to artificially increase that pressure will raise the boiling point of a liquid. (b) Boiling point is dependent upon the strength of the bonds between its molecules. For this reason, adding a solute to the liquid will create stronger bonds between molecules, raising the solution’s boiling point without increasing pressure.

1,429.

The strength of an electromagnet increases with

Increases in the number of turn of the coil

Decreases in current with the coil

Increases in the distance between the pole

Increases in current without the coil

View answer & explanation

Correct answer is A

No explanation has been provided for this answer.

1,430.

A radioactive source emits X–rays of very short wavelength (10 -13m ). what is the frequency of these rays?

2 × 10¹⁸HZ

3 × 10 ¹⁹HZ

3 × 10²¹HZ

3 × 10^-19HZ

View answer & explanation

Correct answer is C

\(Wavelength (\lambda) = 10^{-13}m\)

Speed of X-ray = speed of light \(C = 3×10^{8}m/s\)

Frequently (f) = ?

\(Using V = f\lambda (or (– f π for electromagnetic wave)\)

\(f = \frac{c}{\lambda} = 3 \times 10^{8} ÷ 10^{-13} = 3 \times 10^{8} \times 10^{13}\)

= \(3 \times 10^{8} \times 10^{13}\)

= \(3 \times 10^{21}Hz\)