Which of the following statements are true about electromagnetic waves?
(A) Accelerated charges radiate electromagnetic waves.
(B) The frequency of the electromagnetic wave equals the frequency of oscillation of the charge.
(C) No material medium is involved in the vibrations of the electric and magnetic fields.
(D) Electromagnetic waves of different wavelengths have different velocities in free space/vacuum.
Choose the correct answer from the options given below:

When the light of frequency \(2 \nu_0\) (where \(\nu_0\) is the threshold frequency) is incident on a photosensitive material, the maximum velocity of electrons emitted is \(v_1\). When the frequency of the incident radiation is increased to \(3 \nu_0\), the maximum velocity of emitted electrons from the same material is \(v_2\). The ratio of \(v_1\) to \(v_2\) will then be :

Select scalar quantities from the following:
A. electric flux
B. Electric current
C. Current density
D. Electromagnetic force
Choose the correct answefrom the options given below:

Two light beams of intensities in the ratio 25:9 are allowed to interfere. The ratio of the intensities of maxima and minima will be

If the forward voltage in a p-n junction diode is increased, the width of the depletion region :

In a large building, there are 20 bulbs of 40 W each, 5 bulbs of 100 W each, 5 fans of 80 W each, and 1 heater of 1 kW. The voltage supply is 220 V. The minimum capacity of the main fuse of the building should be

Arrange the given associated wavelengths (\(\lambda_1, \lambda_2, \lambda_3 \text{ and } \lambda_4\)) of radiations with the part of the electromagnetic spectrum in decreasing order of magnitude:
(A) \(\lambda_1\) used to detect fracture in bones
(B) \(\lambda_2\) used to kill germs in water purifiers
(C) \(\lambda_3\) used to treat muscular strain
(D) \(\lambda_4\) used to transmit voice communication
Choose the correct answer from the options given below:

Light with an energy flux of \( 18 \text{ W/cm}^2 \) falls at normal incidence on a non-reflecting surface of area \( 20 \text{ cm}^2 \). If the light falls for 30 minutes on the surface, find the total momentum delivered to the surface.

Which is NOT a major characteristic feature of biodiversity 'Hot Spot'?

'Barnacles' growing on the back of whale is a classical example of :

The function \(f(x)=2 x^3-3 x^2-12 x+4\) has :

Read the passage carefully and answer the questions
Amines are considered as derivatives of ammonia obtained by replacement of hydrogen atoms with alkyl or aryl groups. In nature they occur among proteins, vitamins, alkaloids and hormones. These can be primary, secondary or tertiary depending on the number of hydrogen groups replaced. They can be prepared from nitro compounds, alkyl halides, nitriles, amides etc. Due to unshared pair of electrons they behave as Lewis bases. Influence of the number of hydrogen atoms at nitrogen atom is displayed in physical properties such as solubility, boiling point and chemical reactions including basicity. Basic character of amines is expressed in terms of their \(K_b\) and \(p K_b\) values. Three classes of amines can be distinguished with p-toluene sulphonyl chloride which reacts with primary and secondary ddu amines. Amino group when attached to benzene ring behaves as an activating and ortho para directing group.
Which of the following is a tertiary amine?

The corner points of a bounded feasible region are \(( 0 , 5 ),( 6 , 1 ),( 1 7 , 2 )\) and \(( 4 , 2 9 )\).
If the maximum value of the objective function \(z=p x+q y\), where \(p>0\) and \(q>0\), occurs at two points \((17,2)\) and \((4,29)\), then the relation between \(p\) and \(q\) is :