Flash light equipped with a new set of batteries, produces bright white light. As the batteries wear out
the light intensity gets reduced with no change in its colour
light colour changes first to yellow and then red with no change in intensity
it stops working suddenly while giving white light
colour changes to red and also intensity gets reduced
If a street light of mass Mis suspended from the end of a uniform rod of length L in different possible patterns as shown in figure, then
pattern A is more sturdy
pattern B is more study
pattern C is more sturdy
all will have same sturdiness
The foil bone has a 14C : 12C ratio, which is [ 1/16 ] of that in a living animal bone. If the half-life time of 14C is 5730 years, then the age of the fossil bone is
11460 years
17190 years
22920 years
45840 years
C.
22920 years
After 5730 years, the number of C14 remaining is th original.
To have ( 1/ 16) original value, it takes (1/2)4, 4 half lives.
Therefore, the bone is 4 × 5730 years = 22920 year old.
If alpha, beta and gamma rays carry same momentum, which has the longest wavelength?
Alpha rays
Beta rays
Gamma rays
None, all have same wavelength
A light emitting diode (LED) has a voltage drop of 2 volt across it and passes a current of 10 mA when it operates with a 6 volt battery through a limiting resistor R. The value of R is
40 kΩ
4 kΩ
200 kΩ
400 kΩ
The minimum potential difference between the base and emitter required to switched a silicon transistor ON is approximately
1 V
3 V
5 V
4.2 V