If the refractive index of water is 1.33, what is the critical angle for a water-air boundary?
36.0 °
40.2 °
41.8 °
48.8 °
62.7 °
Correct answer is D
No explanation has been provided for this answer.
The cap will be positively charged and the will be negatively charged
The cap will be negatively charged and the leaf will be positively changed
The cap and the leaf will be positively charged
The cap and the leaf will be negatively charged
none
Correct answer is D
No explanation has been provided for this answer.
1320m
660m
400m
330m
165m
Correct answer is B
No explanation has been provided for this answer.
If the size of the hole of a pinhole camera is increased, the image formed becomes
brighter and blurred
brighter and larger
brighter and sharper
blurred and duller
blurred and larger
Correct answer is E
No explanation has been provided for this answer.
If the temperature of a resistance wire is gradually increased, its resistance will
decrease gradually
first increase and then decrease
first increase and then remain the same
increase gradually
remain the same
Correct answer is C
No explanation has been provided for this answer.