Physics NCERT Exemplar Solutions Class 12th Chapter Nine

A string of area of cross – section 4 mm² and length 0.5 m is connected with a rigid body of mass 2 kg. The body is rotated in a vertical circular path of radius 0.5m. The body acquires a speed of 5 m/s at the bottom of the circular path. Strain produce in the string when the body is at bottom of the circle is________* 10^-5.

(use young's modulus 10¹¹ N/m² and g = 10 m/s²)

The power of lens (biconvex) is 1.25 m^-1 in particular medium. Refractive index of the lens is 1.5 and radii of curvature are 20 cm and 40 cm respectively. The refractive index of surrounding medium:

In a compound microscope, the magnified virtual image is formed at a distance of $25\mathrm{c}\mathrm{m}$ from the eye-piece. The focal length of its objective lens is $1\mathrm{c}\mathrm{m}$ . If the magnification is 100 and the tube length of the microscope is $20\mathrm{c}\mathrm{m}$ , then the focal length of the eyepiece lens (in $\mathrm{c}\mathrm{m}$ ) is

The aperture of the objective is 24.4 cm. The resolving power of this telescope, if a alight of wavelength 2440 $\stackrel{o}{A}$  is used to see the object will be

The refracting angle of a prims is  A and refractive index of the material of the prism is cot (A/2). Then the angle of minimum deviation will be

Given below are two statements : One is labeled as Assertion A and the other is labeled as Reason R.

Assertion A : Product of Pressure (P) and time (t) has the same dimension as that of coefficient of viscosity.

Reason R : Coefficient of viscosity = $\frac{Force}{Velocitygradient}$

Choose the correct answer from the options given below:

If the potential barrier across a p-n junction is 0.6 V. Then the electric field intensity, in the depletion region having the width of 6 * 10^-6m, will be________ * 10⁵ N/C.

The X-Y plane be taken as the boundary between two transparent media M₁ and M₂. M₁ in $z\ge 0$  has a refractive index of $\sqrt[]{2}$  and M₂ with Z < 0 has refractive index of $\sqrt[]{3}.$ A ray of light travelling in M₁ along the direction given by the vector $\overrightarrow{P}=4\sqrt[]{3}\widehat{i}-3\sqrt[]{3}\widehat{j}-5\widehat{k},$  is incident on the plane of separation. The value of difference between the angle of incident in M₁ and the angle of refraction in M₂ will be_______ degree.

A wire of length 314cm carrying current of 14A is bent to form a circle. The magnetic moment of the coil is_________ A -m². [Given π = 3.14]

Two light beams of intensities 4I and 9I interfere on a screen. The phase difference between these beams on the screen at point A is zero and at point B is . The difference of resultant intensities, at the point A and B, will be_________I.