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Three resistors of 6.0 Ω, 2.0 Ω and 4.0 Ω respectively are joined together as shown in the figure. The resistors are connected to an ammeter and to a cell of emf 6.0 V.

The effective resistance of the circuit is:

Which of the following relations represent the Ohm's law?

$V=$Voltage, $I=$Current, $R=$Resistance

A small object stuck on the surface of a glass sphere $(\mu =1.5)$ is viewed from the diametrically opposite position.





Considering the proper sign convention, image position for observer will be

The figure shows two coaxial circular loops $1$ and $2$ carrying equal current $I$, form the same solid angle $\theta$ at point $O$. If $B_1$ and $B_2$ are the magnetic fields produced at point $O$ due to loop $1$ and $2$ respectively, then,

Find the equivalent resistance between $\text{A}$ and $\text{B}$.

Consider a long wire carrying a time varying current $i=kt(k>0)$. A circular loop of radius $a$ is placed with its center at a distance $d$ from the wire $(a<<d)$. The magnetic flux through the loop is

The focal length of a convex lens in air is $10\text{cm}$. Find its focal length in water.

Given : Refractive index of lens and water are ${\mu }_g=\frac{3}{2}$ and ${\mu }_w=\frac{4}{3}$ respectively.

Why doesn't mirror formula has a negative sign similar to lens formula ?

Answer in Brief:

Write the objectives of The Water Act.

A force of 10 gf is applied on a body of mass 98g. Calculate the acceleration of the body [g = 9.8 m/s² = 980 cm/s²]

By error, a student places a moving-coil voltmeter $V$ (nearly ideal) in series with the resistance in a circuit in order to read the current, as shown. The voltmeter reading will be

How can the work done be measured when force is applied at an angle to the direction of displacement.

A ray of light passes from medium 1 to medium 2. Which of the following quantities of the refracted ray will differ from that of the incident ray: speed, intensity, frequency, and wavelength?

In the figure shown, $AB$ is a plane mirror of length $40\text{cm}$ placed at height of $40\text{cm}$ from the ground. There is a light source at a point on the ground. Find the minimum height of a man (eye height) required to see the image of the source if he is standing at a point $P$ on the ground as shown in the figure.

When we enter a dark room, what happens to the size of the pupil?

A virtual image, we always say, cannot be caught on a screen. Yet when we ‘see’ a virtual image, we are obviously bringing it on to the ‘screen’ i.e., retina of our eye. Is there a contradiction? [3 MARKS]

Which wair is used in the Fuse? Give reason.

It is proposed to use the nuclear fusion reaction ${}_1{\text{H}}^2+{}_1{\text{H}}^2\to {}_2{\text{He}}^4$ in a nuclear reactor of $200\text{MW}$ rating. If $25\text{\%}$ of energy from the above reaction is used in the reactor, how many grams of deuterium will be needed per day?

$[\text{mass of}{}_1{\text{H}}^2=2.0141\text{amu},\text{mass of}{}_2{\text{He}}^4=4.0026\text{amu},1\text{amu}{c}^2=931.5\text{MeV}]$

A conducting rod is rotating about one end, in a plane perpendicular to a uniform magnetic field, with constant angular velocity. The correct graph between the induced emf $\left(e\right)$ across the rod and time $\left(t\right)$ is -

Magnetic field lines due to a conductor is as shown below. Then which of the following is true?

If $ab$ is the wavefront at time $t=0$ and $cd$ is the wavefront at time $t=t_1$. Find the direction of propagation of light.

Three resistances are connected as shown in diagram through the resistance 5 $\Omega$, a current of 1 A is flowing :

(i) What is the current through the other two resistors?

(ii) What is the potential difference (p.d.) across AB and across AC ?

(iii) What is the total resistance ? [5 MARKS]

The magnetic flux density $B$ is changing its magnitude at a constant rate $dB/dt$. A given mass $m$ of copper having resistivity $\rho$ and density $d$, drawn into a wire of radius $a$ and formed into a circular loop of radius $r$ is placed perpendicular to the field $B$. The induced current in the loop $i$ is :

Why is the wavelength of blue light different from that of red light?

A dielectric rod of mass M and length L is kept in uniform electric field $E_0$ as shown in figure. Half of the rod is charged to +Q and other half to -Q uniformly. Frequency of SHM if rod is rotated slightly and released is

A Galvanic cell is set up from a Zinc bar weighing 100g and 1L of 1M $CuS{O}_4$ solution. How long would the cell run assuming it delivers a steady current of 1 amp?

A glass slab $(\mu =1.5)$ of the thichness 2 cm is placed on a spot. The shift of spot if it is viewed from top is

The potential difference applied to an X -ray tube is 5 kV and the current through it is 3.2 mA. Then the number of the electrons striking the target per second is

What resistance must be connected in parallel to a $8\Omega$ resistance to make the effective resistance equal to $4.8\Omega$?

A fish is swimming in a river at a depth of $20cm$ from the surface of the water. The refractive index of water is $4/3$. An eagle flying above the water will see the fish at a depth of ___$cm$

An optician while testing the eyes of a patient keeps a chart of letters 3 m behind the patient and asks him to see the letters on the image of chart formed in a plane mirror kept at distance 2 m in front of him. At what distance is the chart seen by the patient ?

A man can open a nut by applying a force of 150 N by using a lever handle of length 0. 4 m. What should be the length of the handle if he is able to open it by applying a force of 60 N?