3.47 x 1018
6.93 x 10 20
3.47 x 1020
6.93 x 1018
Correct answer is A
The number of disintegration,∆N in time interval At, is given by
- ∆N = N∆t
Where N is the number of atoms present at the time t
But ^ = (0.693)/T
= 0.693 ÷ 20
= 0.0347
∴ ∆N = 0.0347 \(\times\) 10\(^20\)
= 3.47 \(\times\) 10\(^18\)
Cancerous cells can be destroyed by?
ultraviolet rays
alpha particules
x - rays
infrared rays
Correct answer is C
Cancerous cells can be destroyed with a high penetrating radiation which is x - rays
5.60 v
24.00 v
0.24 v
2.40 v
Correct answer is D
Number of tunes, n = 500
Area, A = 0.2m + 0.2m = 0.4m2
change of flux density A B
= 1.0 - 0.4 = 0.6T
Tune, t = 5 su
Induced emf, ξ = (AB AN)/AT
(0.6 x 0. 04 x 500)/5
= 2.4v
3.86 x 105J
3.56 x 105J
1.80 x 104J
2.16 x 105J
Correct answer is D
Energy generated = power X time = 60w x 1h = 60 x 60 x 60 ws = 216000j = 2.16 x 105J
close up
become positively charged
become negatively charged
open further
Correct answer is A
The leaves collapse as the positive charges on the rod neutralize the negative charges on the electroscope.