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In which of the following devices, the eddy current effect is not used?
Two point charges A and B, having charges +Q and −Q respectively, are placed at a certain distance apart and the force acting between them is F. If 25% charge of A is transferred to B, then the force between the charges becomes:
The current in an inductor of self-inductance $4 \text{ H}$ changes from $4 \text{ A}$ to $2 \text{ A}$ in $1 \text{ s}$. The emf induced in the coil is:
Dimensional formula for volume elasticity is
What is the flux of electric field $\vec{E} = 3 \times 10^3 \hat{i}$ N/C through a square of 10 cm on a side whose plane is parallel to the yz-plane?
A point charge +10 μC is at a distance 5 cm directly above the centre of a square of side 10 cm, as shown in the figure. What is the magnitude of the electric flux through the square?
Each of the two strings of lengths $51.6 \text{ cm}$ and $49.1 \text{ cm}$ is tensioned separately by $20 \text{ N}$ of force. The mass per unit length of both strings is the same and equals $1 \text{ g/m}$. When both the strings vibrate simultaneously, the number of beats is:
The force between two small charged spheres having charges of $2 \times 10^{-7}$ C and $3 \times 10^{-7}$ C placed 30 cm apart in the air is:
The velocity $v$ of a particle at time $t$ is given by $v = at + \frac{b}{t+c}$, where $a$, $b$ and $c$ are constants. The dimensions of $a$, $b$ and $c$ are respectively:
Which one has the dimensions different from the remaining three?
Six charges +q, -q, +q, -q, +q and -q are fixed at the corners of a hexagon of side d as shown in the figure. The work done in bringing a charge q₀ to the centre of the hexagon from infinity is: (ε₀ - permittivity of free space)
A tuning fork with a frequency of $800 \text{ Hz}$ produces resonance in a resonance column tube with the upper end open and the lower end closed by the water surface. Successive resonances are observed at lengths of $9.75 \text{ cm}$, $31.25 \text{ cm}$, and $52.75 \text{ cm}$. The speed of the sound in the air is:
Taking into account the significant figures, what is the value of $9.99\text{ m} - 0.0099\text{ m}$?
Of the following quantities, which one has dimensions different from the remaining three?
In the above diagram, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively, are through the directions:
Light with an average flux of 20 W/cm² falls on a non-reflecting surface at normal incidence having a surface area of 20 cm². The energy received by the surface during a time span of 1 minute is:
The ratio of the amplitude of the magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to:
A parallel plate capacitor is charged by connecting it to a battery through a resistor. If $i$ is the current in the circuit, then in the gap between the plates:
A rod of length $L$ rotates with a small uniform angular velocity $\omega$ about its perpendicular bisector. A uniform magnetic field $B$ exists parallel to the axis of rotation. The potential difference between the centre of the rod and an end is:
The electric field of an electromagnetic wave in free space is given by $\vec{E} = 10 \cos(10^7 t + kx) \hat{j}$ V/m, where $t$ and $x$ are in seconds and meters respectively. It can be inferred that: (1) The wavelength $\lambda$ is $188.4 \text{ m}$. (2) The wave number $k$ is $0.33 \text{ rad/m}$. (3) The wave amplitude is $10 \text{ V/m}$. (4) The wave is propagating along $+x$ direction. Which one of the following pairs of statements is correct?