Physics is Easy

Question of the day A
7kg mass sliding on a frictionless surface explodes into three equal masses. After the explosion, the velocities of the three masses are:

Question of the day

Find the capacitance

Question of Day

Suppose that the current is a function of time with I(t)=a+b t ,
where a and b are positive constants. What is the induced emf in the Loop and the direction of the induced current?

Questions of the day

An electromagnetic wave enters a medium of lower refractive index.
Three statements are made:
I The wavelength of the wave has increased.
II The frequency of the wave has decreased.
III. The speed of the wave has increased.

What is true about the properties of the wave?

A

I and II only

B

I and III only

C

II and III only

D

I, II and III

Type your answer in comment

Which of the following is not one of the seven basic SI units?
ampere
kilogram
kelvin
feet

Solution

Seven basic SI units are
kg,s,Ampere,kelvin, mole,candela,metre

Feet is not SI unit
Option 4 is correct

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Questions Find the angle that is supplementary to
a)179°
b)180°
c)1°
d)181°

Try it yourself

Which SI unit would be used to report the mass of a child?
a)mole, mol
b) liters, L
c) kilograms, kg
d) kelvin, K

Solution: SI unit of mass is Kg i.e kilogram according to MKS system .So to report the mass of a child kg is used.

Question: 6. An electromagnetic wave enters a medium of lower refractive index.Three statements are made
1. The wavelength of the wave has increased.
II. The frequency of the wave has decreased.
III. The speed of the wave has increased.
What is true about the properties of the wave
A. I and II only
B. I and III only
C. II and III only
D. I, II and III

Explanation

When an electromagnetic wave enters a medium of lower refractive index (n decreases):

V=c/n

Speed (v) of light increases, because

Lower n → higher v

Frequency (f) of light does NOT change when light goes from one medium to another.

Frequency is decided by the source, not the medium.

Wavelength (λ) changes according to

Since speed increases and frequency remains constant, wavelength increases.

Now check the statements:

I. Wavelength has increased ✅ True
II. Frequency has decreased ❌ False
III. Speed has increased ✅ True

Correct answer:

B. I and III only ✔️