anileducation

A capacitor with capacitance C=100μF is connected in series with a resistor of resistance R=1MΩ. If the capacitor is initially (t=0s) charged with a potential difference of ε=20V across its plates, how much time will pass before the potential difference drops by 25% to V=15V (assuming the capacitor is disconnected from power) ?

Two resistors, R1=25Ω and R2=50Ω, are in a parallel circuit. What is their resultant resistance R12 ?

Light of wavelength 615 nm falls on a double slit, and the first bright fringe of the interference pattern is seen at an angle of 16.8° from the central maximum. Find the separation between the slits.
 𝜇m

A laser beam is incident on two slits with a separation of 0.195 mm, and a screen is placed 5.20 m from the slits. If the bright interference fringes on the screen are separated by 1.56 cm, what is the wavelength of the laser light?
 nm

A double slit separated by 0.0586 mm is placed 1.35 m from a screen.

In a Young's double-slit experiment, 633-nm laser light illuminates two slits separated by a distance of 3.28 ✕ 10−5 m.

Twice a number (z)added to 21 is equal to 9 times the number added to 7. What is the number?

A.  z = -4

B.  z = -2

C.  z = 2

D.  z = 4