The half-life of a radio-active element is 9 days, what fraction of atoms has decayed in 36 days?
\( \frac{1}{16} \)
\( \frac{1}{4} \)
\( \frac{1}{2} \)
\( \frac{15}{16} \)
Correct answer is D
No explanation has been provided for this answer.
81N
121N
162N
324N
Correct answer is A
No explanation has been provided for this answer.
What is the angle of dip at the magnetic equator
\( 45^{\circ} \)
\( 0^{\circ} \)
\( 90^{\circ} \)
\( 180^{\circ} \)
Correct answer is B
The angle of dip dip is the angle which the resultant earth's magnetic field makes with the horizontal.
At the magnetic equator, which is entirely along the horizontal this angle is zero
5.76 x 104J
1.60 x 104J
3.60 x 103J
1.60 x 102J
Correct answer is A
Electrical Energy = IVt
= 4 x 240 x (1 x 60)
= 57600J
= 5.76 x 104J
40Hz, 80Hz, 120Hz
80Hz, 160Hz, 240Hz
180Hz, 360Hz, 540Hz
369Hz, 180Hz, 90Hz
Correct answer is A
in vibrations in string, the fundamental frequency happens to be the first harmonic, and is given as
f0 = V/2l.
Where V = Velocity of the sound wave, I = Length of the string.
The second harmonic is the first overtone given by
f1 = V/l = 2f0 ;
and the third harmonic happens to be the second overtone, given by
f2 = 3V/2l = 2f0.
Thus if V = 120m/s and l = 1.5m
Thus f1 = 2f0 = 2 x 40 = 80Hz
Thus f2 = 3f0 = 3 x 40 = 120Hz
Thus we have in order, 40Hz, 80Hz, 120Hz