In the diagram above, the ratio of he electric power dissipated in the 6Ω and the 3Ω resistor respectively is
- A. 2:1
- B. 2:2
- C. 1:3
- D. 1:2
To protect a material from the influnce of an external magnetic field, the materials should be kept
- A. square steel ring
- B. triangular zinc ring
- C. soft iron ring
- D. loop of copper wire
The difference between X-rays and gamma rays is that
- A. x-rays are more penetrating than gamma rays
- B. x-rays are electromagnetic radiations while gamma rays are negatively charged radiation
- C. x-rays have higher frequencies than gamma rays
- D. x-rays arise from energy changes in the electronic structure of atoms while gamma rays come from the nucleus
Given three capacitors 0.3μF, 0.5μF and 0.2μF, the joint capacitance when arranged to give minimum capacitance is
- A. 0.1μF
- B. 0.3μF
- C. 1.0μF
- D. 0.5μF
Electrical appliances at home are normally earthed so that?
- A. the appliances are maintained at a lower p.d than the earth
- B. both the a.c and d.c sources can be used
- C. a person touching the appliances is safe from electric shock
- D. the appliances are maintained at a higher p.d than the earth
If 16mA of current flows through a conductor in one second, the number of electron transported per seconds is
[1 electronic charge = 1.6 x 10-19C]
- A. 1.00 x 1020
- B. 2.56 x 10-18
- C. 2.56 x -17
- D. 1.00 x 1017
The instrument used for securing a large number of similar charges by induction is called
- A. electrophorus
- B. capacitor
- C. proof-plane
- D. electroscope
A steady current of 2A flows in a coil of emf 12V for 0.4s. A back emf of 3V was induced during this period. The stored energy in the loop that can be utilized is
- A. 9.6J
- B. 2.4J
- C. 12.0J
- D. 7.2J
Which of the following is an electrolyte?
- A. Paraffin
- B. Sugar solution
- C. Grape fruit
- D. Alcohol
The energy stored in an inductor of inductance 5mH when a current of 6A flows through it is
- A. 9.0 x 10-3J
- B. 9.0 x 10-2J
- C. 1.4 x 10-2J
- D. 1.8 x 10-3J
Flourescent tubes produces light by the
- A. excitation of gas molecules
- B. conduction of solar energy
- C. refraction of light by gas molecules
- D. thermal agitation of electron in the tubes
| The binding energy of helium | 4 | He is |
| 2 |
[atomic mass of proton = 1.00783U,
atomic mass of neutron = 1.00867U]
- A. 4.033U
- B. 2.017U
- C. 0.033U
- D. 0.330U
In a tuned radio receiver R, L, C series circuit for resonance, the inductive and capacitive reactance XL and XC respectively are related as
- A. XL = XC
- B. XL = 1/2XC
- C. XL = 1/XC
- D. XL = 2XC
In a reverse biased junction diode, current flows in by
- A. positive holes alone
- B. majority carriers
- C. electron alone
- D. minority carriers
The particle and wave nature of matter are demonstrated in the equation
- A. λ = hc/E
- B. λ = h/P
- C. λ = c/f
- D. λ = 2 d sin θ
A moving coil galvanometer has a full-scale deflection of 3A equivalent to 30o deflection. The sensitivity of the instrument is
- A. 33.0
- B. 0.1
- C. 90.0
- D. 10.0
X rays can be used in the study of crystal structure because they
- A. have a very long-reaching wavelength
- B. have extremely short wavelength
- C. are invisible
- D. are very fast
For semi conductor to have negative temperature coefficient of resistance implies that
- A. their resistance decrease with temperature
- B. The resistance increase with temperature
- C. their resistance is constantly changing with temperature
- D. they have electrons and holes at high temperature
An a.c circuit of e.m.f 12V has a resistor of resistance 8Ω connected in series to an inductor of inductive reactance 16Ω and a capacitor capacitive reactance 10Ω. The current flow in the circuit is
- A. 1.4A
- B. 1.2A
- C. 12.0A
- D. 14.0A
A radioisotope has a decay constant of 10\(^{-7}\)s\(^{-1}\). The average life of the radioisotope is
- A. 1.00 x 107s
- B. 6.93 x 106s
- C. 1.00 x 10-7s
- D. 6.93 x 107s
A generator manufacturing company was contracted to produce an a.c dynamo but inadvertently produced a d.c dynamo. To correct this error, the
- A. armature coil should be made of silver
- B. commutator should be replaced with slip ring
- C. commutator should be replaced with split rings
- D. armature coil should be made of aluminium