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A combination of secondary cells has an equivalent EMF of 2 V. Due to long use they have a large equivalent resistance of 400 $\Omega$. What maximum current can be drawn?

An aluminum wire of length $60\text{cm}$ is joined to a steel wire of length $80\text{cm}$ and stretched between two fixed supports. The tension produced is $40\text{N}$. Cross-sectional area is $1{\text{mm}}^2$ (steel) and $3{\text{mm}}^2$ (aluminum). Minimum frequency of the tuning fork which can produce standing waves with the joint as a node is nearly equal to



(density of $Al=2.6{\text{g cc}}^{-1}$ and density of steel $=7.8{\text{g cc}}^{-1})$

A cylindrical conductor of radius $2\text{cm}$ is surrounded by another hollow cylindrical conductor of radius $20\text{cm}$. If the length of both the cylinders is $4.6\text{cm}$, then what is the capacitance of this system?

$(\ln 10=2.3)$

Sir can you please give me some examples of measurements which can be measured directly by our sensory organs without using any instruments.I got this doubt on seeing the introduction video.

A laser beam has intensity $2.5\times {10}^{14}$${\text{Wm}}^{-2}$. The amplitudes of electric and magnetic fields in the beam are :

A body is projected vertically upwards. The times corresponding to height h while ascending and while descending are $t_1$ and $t_2$ respectively. Then, the velocity of projection is:

The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents of a photon with the most energy?

1. 0.785

Which of the following is not possible?

A rigid body of mass $m\text{kg}$ is lifted with uniform velocity by a man to a height of $1\text{m}$ in $30\text{seconds}$. Another man lifts the same mass with uniform velocity to the same height in $60\text{seconds}$. The work done on the body against gravity by them are in the ratio

Electric field in space is given as $\overrightarrow{E}=-2x^2\hat{i}+y\hat{j}-2z\hat{k}$. If potential of point $P(3,2,0)$ is $8$ volt, then potential at origin is:

Whenever the magnetic flux () linked with a coil changes the emf is induced in the circuit, This emf lasts

A thin square plate of side $4\text{cm}$ and mass $m$ has a moment of inertia $I_{\text{Sq}}$ about the line $AB$ as shown in figure. It is then reformed into a rectangle of length $8\text{cm}$ and breadth $2\text{cm}$ with a moment of inertia $I_{\text{Rect}}$ about the line $CD$ as shown in the figure. What is the value of the ratio $\frac{I_{\text{Sq}}}{I_{\text{Rect}}}?$

An isosceles triangular glass prism stands with its base in water as shown. The angles that its two equal sides make with the base are $\theta$ each. An incident ray of light parallel to the water surface internally reflects at the glass-water interface and subsequently reemerges into the air. Take the refractive indices of glass and water to be $3/2$ and $4/3$ respectively. The least value of $\theta$ for this to happen must be

Figure 3.23 gives the x-t plot of a particle executing
one-dimensional simple harmonic motion. (You will learn about this
motion in more detail in Chapter14). Give the signs of position,
velocity and acceleration variables of the particle at t = 0.3
s, 1.2 s, – 1.2 s.

(Fig: 3.23)

The magnetic field in a plane EM wave is given by $B_y=2\times {10}^{-7}sin(0.5\times {10}^{3}x+1.5\times {10}^{11}t)T$. What is the expression for the electric field ?

An $EM$ wave from air enters a medium. The electric fields are $\overrightarrow{E_1}=E_{01}\hat{x}\cos \left[2\pi f(\frac{z}{c}-t)\right]$ in air and $\overrightarrow{E_2}=E_{02}\hat{x}\cos \left[k\right(2z-ct\left)\right]$ in medium, where the wave number $k$ and frequency $f$ refer to their values in air. The medium is non-magnetic. If ${\epsilon }_{r1}$ and ${\epsilon }_{r2}$ refer to relative permittivities of air and medium respectively, which of the following options is correct?

In the figure below, the switches $S_1$ and $S_2$ are closed simultaneously at $t=0$ and a current starts to flow in the circuit. Both the batteries have the same magnitude of the electromotive force (emf) and the polarities are as indicated in the figure. Ignore mutual inductance between the inductors. The current $I$ in the middle wire reaches its maximum magnitude $I_{max}$ at time $t=\tau$. Which of the following statement(s) is (are) true?

A rod of mass $M$ and length $2L$ is supended at its middle by a wire. It exhibits torsional oscillations. If two masses each of $m$ are attached at distance $\frac{L}{2}$ from its centre on both sides, it reduces the oscillation frequency by $20\%$. The value of ratio $\frac{m}{M}$ is close to

What is the maximum extension in the spring shown in figure?

If an electron emitted from photo-electric emissions revolves in a circle when exposed to a uniform transverse magnetic field of strength $B=5.2\times {10}^{-7}\text{T}$ with a maximum radius of $5\text{m}$, find the wavelength of incident energy if work function is $2.5\text{eV}$ $(\text{Use}hc=12400\text{J}\dot{A})$

If the frequency of the $2^{nd}$ and $5^{th}$ harmonics of string fixed at both ends differ by $108\text{Hz}$. What is the fundamental frequency of the string?

A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity ‘g’, the reading on the spring balance will be

A rod of mass m and length L is kept on two connection points a and b in a uniform magnetic field B. As soon as switch S is closed rod jumps to height H. Charge flown through the battery is

Given that $\overrightarrow{P}+\overrightarrow{Q}+\overrightarrow{R}=0$. Two out of the three vectors are equal in magnitude. The magnitude of the third vector is $\sqrt{2}$ times that of $1^{\text{st}}$ and $2^{\text{nd}}$ vector. Which of the following can be the angles between these vectors?

Consider the circuit shown in figure (32-E19a). Find (a) the current in the circuit, (b) the potential drop across the 5$\Omega$ resistor, (c) the potential drop across the 10$\Omega$ resistor. (d) Answer the parts (a), (b) and (c) with reference to figure (32-E19b)

1. 2900

A circular current carrying coil has a radius $R$. The distance from the centre of the coil on the axis where the magnetic induction will be ${\left(\frac{1}{8}\right)}^{th}$ to its value at the centre of the coil is

A block of mass $M=40\text{kg}$ is released on a smooth incline from the point shown in the figure. After travelling through a length of $30\text{cm}$, it strikes an ideal spring of force constant $k=1000\text{N/m}$. It compresses the spring and then gets pushed back. How much time after its release will the block be back again to the point of release?

[Take $g=10{\text{m/s}}^2$]

The speed of block $A$ in the system shown in the figure is (String is massless and inextensible)