A substance has a half of 3mins. after 6mins. the count rate was observed to be 400. What was its count rate at zero time?
A200
B1200
C1600
D2400
View Explanation & Discuss
Question 944
jamb1990
What precaution should a manufacturer take to ensure that energy loss in a transformer is minimized?
Athe winding of the transformer should be made of high resistance wire
Bthe core should be made of thin sheets of metal
Cno magnetic material should be used to make the core
Dthe flux linking the primary with the secondary coils should be minimum
View Explanation & Discuss
Question 945
jamb1990
The number of neutrons contained in the nucleus \(^{238}_{92}U\) is
A92
B146
C238
D330
View Explanation & Discuss
Question 946
jamb1990
A 0 - 10mA galvanometer with a coil resistance of 30\(\Omega\) can be converted to a 0 - 10A ammeter by using
A0.03\(\Omega\) series resistor
B0.03\(\Omega\) shunt resistor
C9.99\(\Omega\) shunt resistor
D9.99\(\Omega\) series resistor
View Explanation & Discuss
Question 947
jamb1990
A lamp is rated 240V, 60W. The resistance of the filament is
A960\(\Omega\)
B16\(\Omega\)
C15\(\Omega\)
D4\(\Omega\)
View Explanation & Discuss
Question 948
jamb1990
Electrical power is transmitted at a high voltage rather than low voltage because the amount of energy loss is reduced due to
Aheat dissipation
Bproduction of eddy currents
Cexcessive current discharge
Dexcessive voltage distance
View Explanation & Discuss
Question 949
jamb1990
Which of the following is most suitable for protecting the circuit of 2000W electric iron connected to a 250V mains?
A13A
B8A
C5A
D3A
View Explanation & Discuss
Question 950
jamb1990
Which of the following is an essential physical property of the wires used for making fuses?
Alow density
Bhigh thermal conductivity
Clow electrical resistivity
Dlow melting point
View Explanation & Discuss
Question 951
jamb1990
The total energy required to send a unit positive charge round a complete electrical circuit is the
Akinetic energy
Bpotential difference
Celectromotive force
Delectrical energy
View Explanation & Discuss
Question 952
jamb1990
When a known standard resistor of 2\(\Omega\) is connected to the 0.0cm end of a meter bridge, the balance point is found to be at 55.0cm. What is the value of the unknown resistor?
A1.10\(\Omega\)
B1.64\(\Omega\)
C2.44\(\Omega\)
D27.50\(\Omega\)
View Explanation & Discuss
Question 953
jamb1990
Three cells each of e.m.f. 1.5v and an internal resistance of 1.0\(\Omega\) are connected in parallel across a load resistance of 2.67\(\Omega\). Calculate the current in the load?
A0.26A
B0.41A
C0.50A
D0.79A
View Explanation & Discuss
Question 954
jamb1990
Which of the following is a vector?
AElectric charge
BElectric field
CElectrical potential difference
DElectrical capacitance
View Explanation & Discuss
Question 955
jamb1990
Which of the following statements are true of an insulated charged body carrying positive charge? i. it contains excess positive charges. ii. it creates an electric field. iii. it possesses potential energy. iv. it carries electric current.
Ai and iv only
Bi and ii only
Ci, ii, iii only
Di, ii, iii and iv
View Explanation & Discuss
Question 956
jamb1990
One of the properties of the earth's magnetic field is that the
Anorth pole lies in the northern hemisphere
Bgeographic and magnetic meridians coincide
Cearth's magnetic flux is entirely horizontal at a place where the magnetic dip is zero
Dearth's magnetic flux is entirely vertical at a place where the magnetic dip is zero
View Explanation & Discuss
Question 957
jamb1990
A sonometer wire of length 100cm under a tension of 10N, has a frequency of 250Hz. Keeping the length of the wire constant, the tension is adjusted to produce a new frequency of 350Hz. The new tension is
A5.1N
B7.1N
C14.0N
D19.6N
View Explanation & Discuss
Question 958
jamb1990
An organic pipe closed at one end is 80cm long. Determine the frequency of the fundamental note assuming that the speed of sound in air is 340ms-1
A106Hz
B213Hz
C318Hz
D425Hz
View Explanation & Discuss
Question 959
jamb1990
In a resonance tube experiment, the effective length of the air column for the first resonance is 20cm when set into vibration by a tuning fork of frequency 480Hz. Neglecting and effect, the velocity of sound in air is
A96ms-1
B255ms-1
C340ms-1
D384ms-1
View Explanation & Discuss
Question 960
jamb1990
When light is incident on an object which is magenta in colour, which of the following colour would be absorbed?
