JEE Main Physics Test- 6 - JEE MCQ

Moseley’s law for characteristic X-ray is  =a(z-b).In this

Cutoff wavelength of X-rays coming from a Coolidge tube depends on the

Two identical capacitors A and B are charged to the same potential V and are connected in two circuits at t = 0 as shown in figure. The charges on the


capacitors at a time = CR are, respectively

A semiconducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be

In a radioactive decay, neither the atomic number nor the mass number changes. Which of the following particles is emitted in the decay ?

Ten grams of kept in an open containg beta-decays with a half-life of 270 days. The weigth of the material inside the container after 540 days will be very nearly

A free neutron decays to a proton but a free proton does not decay to a neutron. This is because

If elements with principle quantum number n>4 were not allowed in nature, the number of possible elements would be

Consider the spectral line resulting from the transition n = in the atoms and ions given below. The shortest wave length is produced by

The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature

The X-ray emission line of tungsten occurs at   The energy difference between K and L levels in this atom is about

The electrical conductivity of a semiconductor increases.
when em radiation of wavelength shorter than 2480 nm is incident on it. The band gap (in eV) for the semiconductor is

The circuit shown in the figure contains tow diodes each with a forward resistance of 50 ohms and with infinite backward resistance. If the battery voltage is 6V, the current through the 100 ohm resistance (in Amperes) is

Which of the following statement is not ture ?

In P.E.E, K_max of electrons is 2.0 eV. If frequency of light is decreased by 20% then K_max is 1.0 eV. Work function of electron emitter is (in eV) :-

When a photosensitive surface is illuminated with light of wavelength λ, the stopping potential is V. When the same surface is illuminated by light of wavelength 2λ, stopping potential is V/4. The threshold wavelength for the surface is nλ, n = ?

The number of possible natural oscillations of air column in a pipe closed at one end of length 85 cm whose frequencies lie below 1250 Hz are: (velocity of sound = 340 ms^–1)

A radar has a power of 1 kW and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. What is the maximum distance upto which it can detect object located on the surface of the earth?
(Radius of earth = 6.4 × 10⁶m)

A Zener diode connected across a source voltage of 12V such that 6V drops across it. The power drawn by zener diode is 2.4 MW, Then what is the maximum value of series resistance connected in the circuit?