JAMB Physics Past Questions & Answers

The pitch of a sound is determined by its frequency. Higher frequencies correspond to higher pitches. For example, a high-pitched sound like a whistle has a higher frequency than a low-pitched sound like a drum.

F = qvB ( force on moving charge in a magnetic field) F = \(\frac{mv^2}{r}\)

equating F

qvB =  \(\frac{mv^2}{r}\)

qB =   \(\frac{mv}{r}\)

qBr = mv 

Therefore, v =   \(\frac{qBr}{m}\)

u = 20 ms-1, t = 15 s
\(S = ut + 1/2 at^2\)
S = 20(15) + \(\frac{1}{2}× a × 15^2\)
∴ S = 300 + 225\(\frac{a}{2}\)

In a controlled thermal fission reactor, control rods are used to absorb excess neutrons and thus control the rate of the nuclear reaction. They do not affect the speed of the neutrons released on fission. The speed of the neutrons is determined by the nature of the fission process itself, not by the control rods.

The process of producing electric current by a changing magnetic field is referred to as electromagnetic induction.

Electromagnetic induction is a phenomenon in which a voltage is generated in a conductor when it is exposed to a changing magnetic field. This voltage can then be used to drive an electric current.

The diagram above is a full wavelength and the length of an open pipe during first overtone equals one wavelength i.e. l = λ

Number of cycles, n = \(2\frac{1}{2} = \frac{5}{2}\)

Length = nλ

λ = \(\frac{Length}{n}\)  =  \(\frac{125}{\frac{5}{2}}\)

Therefore, λ = 50cm = 0.50m.

The magnitude of the electric field strength at any point between the plates is not directly proportional to the magnitude of the charge on each plate. Instead, it is directly proportional to the charge density (charge per unit area) on the plates. Therefore, if the charge on the plates is increased while keeping the area of the plates constant, the electric field strength will increase. However, if the area of the plates is also increased such that the charge density remains constant, the electric field strength will not change

The frequency of a sound wave is proportional to the tension of the string. If two instruments have the same frequency, but one has a tighter string, then the instrument with the tighter string will have a higher pitch.

The other factors listed, such as the size of the instrument, the material of the instrument, and the shape of the instrument, will also affect the pitch of the instrument, but they will have a smaller effect than the tension of the string.

Resonance in an AC circuit occurs when the inductive reactance (XL) is equal to the capacitive reactance (XC). This is because at this point, the two reactances cancel each other out, leaving only the resistance of the circuit. As a result, the impedance of the circuit is minimized.