Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examinations.
11. Consider the following statements: 1. Largest fraction of electricity generated in India is coal based 2. Majority of imported coal in India is used in electricity production Which among the above statements is / are correct?
[A] Only 1 [B] Only 2 [C] Both 1 & 2 [D] Neither 1 nor 2
Notes: Bits on Coal import and Usage First statement is correct – We are more dependent on coal Around 54 % of the total installed electricity generation capacity is coal based in India and 67% of the capacity planned to be added during the 11 Five year Plan period (2007-12), is also coal based. Furthermore, over 70 % of the electricity generated is from coal based power plants. These data prove the coal dependence of Indian economy. Second statement is incorrect – Maximum use of imported coal is in Iron and Steel Industry At present, India imports about 85 million tons of coal. Out of this, about 25 million tons is metallurgical coking coal for the iron & steel industry. The balance is thermal coal used by power plants (50%), cement industry (17%) and other industries (33%). Presently, main sources of thermal coal imports are Indonesia, Australia, New Zealand and South Africa. Canada, Mozambique and the USA are amongst the emerging supply sources. Present coal handling capacity at the ports is around 85-90 million tons per annum. This has to be augmented to at least 120 million tons per annum in next two years. Further it has to be doubled the present capacity by the end of the 12 Five Year Plan period.
12. Consider the following:
Convex lens
Concave lens
Concave mirror
Convex mirror
Plane mirror
Which of the above can form a real image of a real object?
[A] Only 1 & 2 [B] Only 1 & 3 [C] Only 2, 3 & 4 [D] Only 1, 3, 4 & 5
Notes: V=√ GM/r G is the Gravitational constant M is the mass of the central body about which the satellite orbits R is the Radius of orbit for the satellite V is the velocity of satellite
14. Consider the following statements:
Co-efficient of rolling friction is usually less than sliding friction.
Static friction is usually greater than sliding friction.
Which of the above statements is/are correct?
[A] Only 1 [B] Only 2 [C] Both 1 & 2 [D] Neither 1 nor 2
Notes: First statement is incorrect because White Gold has more Zinc, whereas Yellow Gold usually contains more Nickel. White Gold has Rhodium coating, whereas Yellow Gold does not have the same. The Rhodium coating makes the White Gold costlier and more durable than Yellow Gold. White gold is an alloy of gold and at least one white metal, nickel, manganese or palladium.
16. With reference to the Milky way galaxy, which among the following statements is / are correct? 1.The Milky Way is a member of the Virgo super cluster 2.The two most massive members of the Virgo super cluster are the Milky Way and the Andromeda Galaxy Choose the correct option from the codes given below:
[A] Only 1 [B] Only 2 [C] Both 1 & 2 [D] Neither 1 nor 2
Notes: A galaxy is a group of large number of stars in the sky which have generally the same origin of evolution, such as our Milky Way. A galaxy may contain billions of stars. A cluster of galaxies, which may have up to 10 or even more galaxies is called a local group. Clusters of galaxies are known as a super galaxy, or a super cluster. This may have up to 50 or even 1,000 galaxies. The Milky Way is a member of the Virgo super cluster. However, before that its is a part of smaller “Local group”. Local Group is the group of galaxies that includes Earth’s galaxy, the Milky Way. The group comprises more than 54 galaxies (including dwarf galaxies), with its gravitational center located somewhere between the Milky Way and the Andromeda Galaxy. The galaxies of the Local Group cover a 10 million light-year diameter and have a binary (dumbbell) shape. This group itself is part of the Virgo Supercluster. Thus second statement is not correct. Virgo Supercluster contains the Virgo Cluster in addition to the Local Group, which in turn contains the Milky Way and Andromeda galaxies. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs. It is one of millions of superclusters in the observable Universe.
17. Consider the following statements with respect to the Thermionic emission: 1. It is caused by electrons or ions that break loose from the metal surface due to heat energy 2. A metal cannot emit thermions at all temperatures Which among the above statements is / are correct ?
[A] Only 1 [B] Only 2 [C] Both 1 & 2 [D] Neither 1 nor 2
Notes: The thermionic emission is cased by electrons or ions that break loose from the metal surface due to heat energy. The minimum heat energy required to make a metal emit an electron (thermion), from its surface is called threshold energy or work function. Electron volt (eV): It is the smallest unit of work and is generally used to measure threshold energy. It is defined as the amount of work done, when a charge of 1.6 × 10–19 coulombs (charge of one electron), moves through two points in an electric field, at a potential difference of one volt. 1 eV = 1.6 × 10–19 C × V = 1.6 × l0–19 J. The minimum temperature at which a particular material emits thermions from its surface on heating is called threshold temperature. A metal cannot emit thermions at all temperatures. The thermions are emitted by a metal only when its temperature is higher than the threshold temperature. (b) 1eV = 1.6 × l0–19 C × 1 V = 1.6 × l0–19 J
18. Which of the following is/are a vector quantity?
Temperature
Work
Kinetic Energy
Momentum
Power
Select the correct option from codes given below:
[A] 2 and 4 Only [B] 4 Only [C] 2, 3, 4 and 5 Only [D] 1, 2, 3, 4 and 5
Notes: A scalar quantity is one which has only magnitude. A vector quantity has both magnitude and direction. Temperature is a comparative measure of hot or cold and is expressed in Celsius, Fahrenheit and kelvin, which represents only magnitude and no direction.Hence temperature, is a scalar quantity. Work is again a scalar quantity because W=F.S where F is force which is a vector quantity and S is displacement which is again a vector quantity.So, dot product of two vector quantity is a scalar quantity. Power is again a scalar quantity as Power is defined as rate of work done P=W/T, A scalar quantity divided by scalar is scalar. Momentum is M=m.v where m is the mass of the body which is scalar quantity and v is the velocity which is vector quantity. Dot product of scalar and vector is vector. K.E=1/2 mv^2, where v^2 is the dot product of two vector quantity and hence is scalar. Dot Product of two vector quantity is scalar.
19. With reference to Voltmeter and Ammeter, consider the following statements: 1. While a Voltmeter is connected in series in a circuit; Ammeter is connected in parallel 2. While resistance of an ideal voltmeter is infinity; resistance of an ideal ammeter is zero Which among the above is / are correct statements?
[A] Only 1 [B] Only 2 [C] Both 1 & 2 [D] Neither 1 nor 2
Notes: Virtual images can also be produced by convex lenses when the object is placed inside the focal length. Virtual images are formed by concave lenses or by placing an object inside the focal length of a convex lens. Plane mirrors always produce virtual images, concave mirrors are capable of producing both real and virtual images. Virtual images are always formed by convex mirrors.
