Which rays are not the portion of electromagnetic spectrum
|
(a) X-rays |
(b) Microwaves |
(c) a-rays |
(d) Radio waves |
Which rays are not the portion of electromagnetic spectrum
|
(a) X-rays |
(b) Microwaves |
(c) a-rays |
(d) Radio waves |
(c) a-rays
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When the accelerating voltage applied on the electrons increased beyond a critical value
|
(a) Only the intensity of the various wavelengths is increased |
| (b) Only the wavelength of characteristic relation is affected |
| (c) The spectrum of white radiation is unaffected |
|
(d) The intensities of characteristic lines relative to the white spectrum are increased but there is no change in their wavelength |
At room temperature, a P-type semiconductor has
|
(a) Large number of holes and few electrons |
|
(b) Large number of free electrons and few holes |
|
(c) Equal number of free electrons and holes |
|
(d) No electrons or holes |
Assertion : Short wave bands are used for transmission of radio waves to a large distance.
Reason : Short waves are reflected by ionosphere
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
Near and far points of a human eye are
|
(a) 0 and 25 cm |
(b) 0 and ¥ |
(c) 25 cm and 100 cm |
(d) 25 cm and ¥ |
A radioactive nucleus
decays to
. Which of the following particles are emitted
|
(a) One alpha and one electron |
(b) Two deuterons and one positron |
|
(c) One alpha and one proton |
(d) One proton and four neutrons |