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Before the electric line is connected to the meter in a house, a fuse of rating (≈ 50 A) is connected in the live wire at the pole or just before the meter. This fuse is called the pole fuse. Its current rating is ≈ 50 A

In set A, the bulbs are connected in series. Thus, when the fuse of one bulb blows off, the circuit gets broken and current does not flow through the other bulbs also. In set B, the bulbs are connected in parallel. Thus, each bulb gets connected to its voltage rating (= 220 V) and even when the fuse of one bulb blows off, others remain unaffected and continue to glow.

(a) The three connecting wires used in a household circuit are:

(i) Live (or phase) wire (L),

(ii) Neutral wire (N), and

(iii) Earth wire (E).

(b) Among them neutral and earth wires are at the same potential.

(c) The switch is connected in the live wire.

Energy consumed per day, E = p × t

= 40 × 12.5

= 500 wh

Energy consumed for 30 days

E = 500 × 30 = 15000 wh = 15 kwh

When current is passed in a wire, the heat produced in it depends on the three factors: (i) on the amount of current passing through the wire, (ii) on the resistance of wire and (iii) on the time for which current is passed in the wire.

(i) Dependence of heat produced on the current in wire: The amount of heat H produced in the wire is directly proportional to the square of current I passing through the wire, i.e., H ∝ I² 

(ii) Dependence of heat produced on the resistance of wire: The amount of heat H produced in the wire is directly proportional to the resistance R of the wire, i.e., H ∝ R

(iii) Dependence of heat produced on the time: The amount of heat H produced in the wire is directly proportional to the time t for which current is passed in the wire, i.e., H ∝ t

All the electrical appliances in a building should be connected in parallel at the mains, each with a separate switch and a separate fuse connected in the live wire so that the switching on or off in a room has no effect on other lamps in the same building.

Given,

Power, p = 60 w

Voltage, v = 250 v

As power, P = VI

I = 60/250 = 0.24 A

Resistance of bulb R = V²/p = 250²/60 = 1041.6 Ω

Now if voltage falls to 200 v, power consumes will be

p = v²/R = 200²/1041.6 = 38.4 W

(a) Q represents Charge and V represents Voltage. 

(b) Electrical Power, P = I²R 

Where I :  current 

And R : Resistance 

Given,

Power, p = 250 w

Voltage, v = 100 v

(i) current through each heater, I = ?

As p = VI

⇒ I = P/V

= 250/100 = 2.5 A

∴ Current taken for the three heaters = 3 × 2.5 = 7.5 A

(ii) resistance for each heater, R = V/I

= 100/2.5 = 40Ω

(iii) Time for which energy is supplied, t = 5h

As, Energy, E = p × t

E = 250 × 5 = 1250 wh

Or 

E = 1.25 kwh

Energy for three heaters = 3 × 1.25 = 3. 75 kwh

(a) Electrical power, P = v²/R

(b) Electrical power, P = I²/R

It means that if the bulb is lighted on a 250 V supply, it consumes 100 W electrical power (which means 100J of electrical energy is converted in the filament of bulb into the light and heat energy in 1 second).

(a) 1Kwh = 1 volt x 1 ampere x 1 hour/1000

(b) 3.6 × 10⁶J

Electrical energy, W = I²Rt joule

144Ω

Solution:

Given, power (p) = 100 w

Potential difference, v = 120 volt

∴ Resistance, r = (v)²/P = (120)²/100 = 144 Ω

An electrical appliance such as electric bulb, geyser etc. is rated with power (P) and voltage (V) which is known as its power rating. For example: If an electric bulb is rated as 50W-220V, it means that when the bulb is lighted on a 220 V supply, it consumes 50 W electrical power.

(a) To calculate the resistance of the appliance, the expression is:

Resistance, R = v²/P

(b) The safe limit of current I is : I = P/v

The paint provides an insulating layer on the metal body of the appliance. To make earth connection therefore, the paint must be removed from the body part where connection is to be made.

Correct answer is (a) zero

Because all other quantities of mechanics can be expressed in terms of length, mass and time through simple relations.

There are two kinds of migrations. 

They are: 

1. Internal migrations 
2. International migrations.

जिन खनिजों में लोहे का अंश पाया जाता है उन्हें लौह धातु खनिज तथा जिन खनिजों में लोहे का अंश नहीं पाया जाता उन्हें बिना लौह धातु खनिज कहा जाता है। कच्चा लोहा, मैंगनीज़, करोमाइट, टंगस्टन धातु खनिज पदार्थ हैं, जबकि सिक्का, बॉक्साइट, टीन, मैग्नीशियम आदि बिना लौह धातु खनिज पदार्थ हैं।

शक्ति के पुराने संसाधनों में कोयला, पेट्रोलियम, प्राकृतिक गैस आदि शामिल हैं। ये समाप्त होने वाले संसाधन हैं। दूसरी ओर सूर्य ऊर्जा, वायु शक्ति, समुद्री लहरें, ज्वार भाटा, भूमिगत ताप ऊर्जा, गोबर शक्ति के नये संसाधन – हैं। ये संसाधन सस्ते, दोबारा पैदा होने वाले तथा प्रदूषण रहित हैं।

पानी (जल) द्वारा पैदा की जाने वाली विद्युत् को पन विद्युत् कहते हैं। नदियों पर बांध बनाकर जल को सुरंगों के मार्ग से भेजकर टर्बाइनें घुमायी जाती हैं। टर्बाइनों के घूमने पर घर्षण के साथ विद्युत् पैदा होती है।

पन विद्युत् का उत्पादन- संसार के बहुत-से देशों में काफ़ी मात्रा में पानी उपलब्ध है। अत: ये देश बड़ी मात्रा में पन विद्युत् का उत्पादन करते हैं। इन देशों में यू० एस० ए०, रूस, जापान, जर्मनी, कनाडा, इंग्लैंड, फ्रांस, इटली, पोलैंड, ब्राज़ील तथा भारत शामिल हैं। संसार की 31% पन विद्युत् केवलं यू० एस० ए० उत्पन्न करता है।

भारत में पन विद्युत् का उत्पादन- भले ही भारत में जल संसाधनों की कमी नहीं है, तो भी भारत संसार की कुल पन-विद्युत् का केवल 1% भाग ही पैदा करता है। भारत के जल संसाधन नदियों तथा नहरों के रूप में विद्यमान हैं। इन्हें मुख्य रूप से दो भागों में बांटा जा सकता है

1. उत्तरी भारत अथवा हिमालय पर्वत से निकली नदियां ।
2. दक्षिण भारत की नदियां।

भारत के उत्तर दिशा की ओर से आने वाली गंगा, ब्रह्मपुत्र और उनकी सहायक नदियां हिमालय की बर्फ पिघलने के कारण सारा साल बहती रहती हैं। इनमें पन विद्युत् पैदा करने की बहुत अधिक क्षमता है। उत्तरी भारत में मिलने वाले इन जल साधनों की क्षमता भारत के कुल सम्भावित जल विद्युत् संसाधन का 18% से भी अधिक है। दूसरी ओर दक्षिण भारत की नदियां वर्षा पर निर्भर करती हैं। इन सभी नदियों की पन विद्युत् तैयार करने की सम्भावित क्षमता कम है।

वितरण- गोआ को छोड़कर भारत के सभी राज्य पन विद्युत् पैदा करते हैं। आन्ध्र प्रदेश, कर्नाटक, महाराष्ट्र, पंजाब, तमिलनाडु, उड़ीसा तथा केरल राज्यों के पास पनविद्युत् तैयार करने की सम्भावित क्षमता बहुत अधिक है। उत्तराखंड तथा हिमाचल प्रदेश जैसे पर्वतीय राज्य पन विद्युत् के सम्भावित संसाधनों में बहुत अधिक धनी हैं। इसलिए इन साधनों को विकसित करने की आवश्यकता है।

• कर्नाटक में नागा-अर्जुन सागर बांध
• उत्तर प्रदेश में गंगा इलेक्ट्रिक ग्रिड सिस्टम
• महाराष्ट्र में टाटा हाइड्रो इलेक्ट्रिक ग्रिडं
• उड़ीसा में हीराकुड बांध
• हिमाचल प्रदेश के मंडी में स्थित पंडोह प्रोजेक्ट तथा भाखड़ा बांध पन-विद्युत् पैदा करने वाले महत्त्वपूर्ण प्रोजेक्ट हैं।

प्राकृतिक संसाधनों का प्रयोग आवश्यकता के अनुसार तथा उचित ढंग से करना चाहिए। किसी भी संसाधन का व्यर्थ प्रयोग नहीं करना चाहिए। इन संसाधनों का प्रयोग करते समय आने वाली पीढ़ियों का भी ध्यान रखना चाहिए।

संसार का सबसे अधिक सोना दक्षिण अफ्रीका पैदा करता है। यह संसार के कुल सोने का लगभग 70 प्रतिशत भाग पैदा करता है।

प्राकृतिक गैस पेट्रोलियम पदार्थों से प्राप्त होती है। जब कोई तेल का कुआं खोदा जाता है तो सबसे ऊपर प्राकृतिक गैस ही मिलती है।

महत्त्व- प्राकृतिक गैस का प्रयोग घरों, वाहनों तथा कई उद्योगों में होता है। मुख्य क्षेत्र-संसार के सभी तेल उत्पादक देशों में प्राकृतिक गैस भी मिलती है। भारत के भी कई क्षेत्रों में प्राकृतिक गैस मिलती है। इन क्षेत्रों में कृष्णा-गोदावरी बेसिन, उड़ीसा के समीप बंगाल की खाड़ी तथा राजस्थान के बाड़मेर क्षेत्र शामिल हैं। इसके अतिरिक्त गुजरात के खंभात और कच्छ क्षेत्र तथा त्रिपुरा में भी प्राकृतिक गैस मिलने की सम्भावना है। देश की लगभग 75% प्राकृतिक गैस बॉम्बे हाई से पैदा होती है।

Correct Answer is: (c) Q ω/2π

With each rotation, charge Q crosses any fixed point P near the ring. Number of rotations per second = ω/2π.

∴ charge crossing P per second = current = Qω/2π.

Self incompatibility Production of unisexual flowers

Following are the factors that accord airways prominence as a mode of transportation:

(i) They are the fastest mode of transportation,

(ii) They are the best means of transport for remote, inaccessible and hostile areas,

(iii) Airways play a vital role in the event of natural and human-made calamities like floods, famines, earthquake, epidemics and war by virtue of their swiftness.

(i) Railways make it possible to conduct multifarious activities like business, sightseeing, pilgrimage along with transportation of goods.

(ii) It is suitable for long-distance travel.

(iii) Plays an important role in national integration.

(iv) Railways bind the economic life of the country.

(v) It accelerates the development of the industry and agriculture.

(vi) Today the railways have become more important than all other means of transport put together.

(a) The Himalayan mountainous regions are unfavourable for the construction of railway lines due to high relief sparse population and lack of economic opportunities. 

(b) It was also difficult to lay railway lines on the sandy plains of western Rajasthan, swamps of Gujarat and forested tracks of Madhya Pradesh, Chhattisgarh, Orissa and Jharkhand. 

Kandla is a tedal port.

Visakhapatnam is the deepest landlocked and well protected port. 

This is a new mode of transport. Pipelines were used in the past to send water to cities and industries. Nowadays crude oil, petroleum products and natural gas are also sent from oil and natural gas fields to refineries, fertilizer factories and big thermal power plants.

Metalled roads are made of cement, concrete or even belumen of coal. They do not go out of use in the rainy season. Therefore, they are called all weather roads.

(i) Kandla in Kuchchh was the first port developed soon after independence of India. 

(ii) It was developed to ease the volume of trade on the Mumbai port, in the wake of loss of Karachi port to Pakistan after the partition. 

(iii) Kandla is a tidal port. 

(iv) It caters to the convenient handling of exports and imports of highly productive granary and industrial belt stretching across the states of Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana, Rajasthan and Gujarat.

(b) Functions of IMF – Exchange stability

The growing importance of road transport in comparison to rail transport is because of the following reasons: 

(i) Construction cost of roads is much lower than that of railways lines. 

(ii) Roads can pass through comparatively more dissected and undulating topography. 

(iii) Road transport is economical in transportation of few persons and relatively smaller amount of goods over short distances.

(iv) It provides door to door services thus the cost of loading and unloading is much lower. 

(v) It is used as feeder to other modes of transport. To reach any destination be it railway station, sea port or airport, one needs to travel through roads.

The growing importance of road transport in comparison to rail transport is because of the following reasons: 

(i) Construction cost of roads is much lower than that of railways lines. 

(ii) Roads can pass through comparatively more dissected and undulating topography. 

(iii) Road transport is economical in transportation of few persons and relatively smaller amount of goods over short distances.

(iv) It provides door to door services thus the cost of loading and unloading is much lower. 

(v) It is used as feeder to other modes of transport. To reach any destination be it railway station, sea port or airport, one needs to travel through roads.

The principal mode of transportation for freight and passengers is railways.

Haldia port was developed as a subsidiary port, in order to relieve growing pressure on the Kolkata port.

Kandla in Kuchchh was the first port developed soon after the independence of India.

Kerala has highest density of roads.

(i) Waterways are the cheapest means of transport. 

(ii) They are most suitable for carrying heavy and bulky goods. 

(iii) It is a fuel-efficient and environment friendly mode of transport. The following waterways have been declared as the National Waterways by the Government:

(i) The Ganga river between Allahabad and Haldia (1620 km)—N.W. No. 1 

(ii) The Brahmaputra river between Sadiya and Dhubri (891 km)—N.W. No. 2 

(iii) The West-Coast Canal in Kerala (Kottapurma-Komman, Udyogamandal and Champakkara canals-205 km)—N.W. No. 3

(i) Kandla in Kuchchh 

(ii) Mumbai port 

(iii) Marmagao port (Goa) 

(iv) Kochchi port 

95% of India’s foreign trade of is handled by the twelve major ports. 

Petroleum and petroleum products.

The Central Board of Film certification is the authority to certify both Indian and foreign films.

Book packets, registered newspapers and periodicals come under the category of second-class mail.

When trade takes place between two countries it is known as international trade. 

(i) It is very important for the development of a country. Advancement of international trade of a country is an index to its economic prosperity. 

(ii) As the resources are space bound, no country can survive without international trade. 

(iii) It enables a country to earn foreign exchange which is needed to import essential goods. It is, therefore, considered the economic barometer for a country.

The length of road per 100 Sq. km of area is known as density of roads. 

(i) The state with highest density of roads – Kerala 

(ii) The state with lowest density of roads – Jammu & Kashmir.

Pipeline transport network is a new arrival on the transportation map of India. Earlier it was used to transport water but these days it is used for the following: 

(i) Transport of crude oil, petroleum products and natural gas from oil and natural gas fields to refineries, fertiliser factories and big thermal power plants is done with the help of pipelines. 

(ii) Even solids can be transported through pipelines when converted into slurry. 

(iii) The far inland locations of refineries and gas-based fertiliser plants could be thought of only because of pipelines. 

(iv) Initial cost of laying pipelines is high but subsequent running costs are minimal. 

(v) It rules out trans-shipment (during transportation) losses or delays.

Three important networks of pipeline transportation in the country 

(i) From oil field in the upper Assam to Kanpur (UP), via Guwahati, Barauni and Allahabad. It has branches from Barauni to Haldia, via Rajbhand, Rajbhand to Maurigram and Guwahati to Siliguri.

(ii) From Salaya in Gujarat to Jalandhar in Punjab, via Viramgam, Mathura, Delhi and Sonipat. It has branches to connect Koyali (near Vadodara, Gujarat) Chakshu and other places. 

(iii) Gas pipeline from Hazira in Gujarat connects Jagdishpur in UP, via Vijaipur in MP. It has branches to Kota in Rajasthan, Shahajahanpur, Babrala and other places in UP.