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प्रश्न
Cathode rays constitute a stream of _______________ .
विकल्प
electrons
protons
positive ions
negative ions
उत्तर
electrons
Cathode rays consist of a stream of fast moving electrons.
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संबंधित प्रश्न
State clearly how photoelectric equation is obtained using the photon pictu.re of electromagnetic radiation.
Write the three salient features observed in photoelectric effect which can be explained using this equation.
Define the term ‘stopping potential’ in relation to photo-electric effect.
Cathode rays are passing through a discharge tube. In the tube, there is ______________ .
Which of the following is true for a cathode ray?
(a) It travels in a straight line.
(b) It emits an X-ray when it strikes a metal.
(c) It is an electromagnetic wave.
(d) It is not deflected by a magnetic field.
The saturation current in a triode valve can be changed by changing _____________ .
A discharge tube contains helium at low pressure. A large potential difference is applied across the tube. Consider a helium atom that has just been ionised due to the detachment of an atomic electron. Find the ratio of the distance travelled by the free electron to that by the positive ion in a short time dt after ionisation.
A molecule of a gas, filled in a discharge tube, gets ionised when an electron is detached from it. An electric field of 5.0 kV m−1 exists in the vicinity of the event. (a) Find the distance travelled by the free electron in 1 µs, assuming there's no collision. (b) If the mean free path of the electron is 1.0 mm, estimate the time of transit of the free electron between successive collisions.
The mean free path of electrons in a gas in a discharge tube is inversely proportional to the pressure inside it. The Crookes dark space occupies half the length of the discharge tube when the pressure is 0.02 mm of mercury. Estimate the pressure at which the dark space will fill the whole tube.
Two discharge tubes have identical material structures and the same gas is filled in them. The length of one tube is 10 cm and that of the other tube is 20 cm. Sparking starts in both the tubes when the potential difference between the cathode and the anode is 100 V. If the pressure in the shorter tube is 1.0 mm of mercury, what is the pressure in the longer tube?
The saturation current from a thoriated-tungsten cathode at 2000 K is 100 mA. What will be the saturation current for a pure-tungsten cathode of the same surface area operating at the same temperature? The constant A in the Richardson-Dushman equation is 60 × 104 Am −2 K−2 for pure tungsten and 3.0 × 104 Am −2 k−2 for thoriated tungsten. The work function of pure tungsten is 4.5 eV and that of thoriated tungsten is 2.6 eV.
On what factor does the maximum kinetic energy of the photoelectrons in a photo cell depend?
Which of the following proves particle nature of light?
The electric field at a point associated with a light wave is given by
E = 200[sin(6 × 1015)t + sin(9 × 1015)t]Vm-1
Given: h = 4.14 × 10-15 eVs.
If this light falls on a metal surface having a work function of 2.50eV, the maximum kinetic energy of the photoelectrons will be ______.
