1
AIEEE 2005
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Starting with a sample of pure $${}^{66}Cu,{7 \over 8}$$ of it decays into $$Zn$$ in $$15$$ minutes. The corresponding half life is
A
$$15$$ minutes
B
$$10$$ minutes
C
$$7{1 \over 2}$$ minutes
D
$$5$$ minutes
2
AIEEE 2005
MCQ (Single Correct Answer)
+4
-1
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than $$2480$$ $$nm$$ is incident on it. The band gap in $$(eV)$$ for the semiconductor is
A
$$2.5$$ $$eV$$
B
$$1.1$$ $$eV$$
C
$$0.7$$ $$eV$$
D
$$0.5$$ $$eV$$
3
AIEEE 2005
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
The intensity of gamma radiation from a given source is $$L$$. On passing through $$36$$ $$mm$$ of lead, it is reduced to $${{\rm I} \over 8}.$$ The thickness of lead which will reduce the intensity to $${{\rm I} \over 2}$$ will be
A
$$9mm$$
B
$$6mm$$
C
$$12mm$$
D
$$18mm$$
4
AIEEE 2005
MCQ (Single Correct Answer)
+4
-1
If the kinetic energy of a free electron doubles, it's deBroglie wavelength changes by the factor
A
$$2$$
B
$${1 \over 2}$$
C
$${\sqrt 2 }$$
D
$${1 \over {\sqrt 2 }}$$
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